Novel materials with extremely durable intercalation of lithium and manufacturing methods thereof

ABSTRACT

Composites of silicon and various porous scaffold materials, such as carbon material comprising micro-, meso- and/or macropores, and methods for manufacturing the same are provided. The compositions find utility in various applications, including electrical energy storage electrodes and devices comprising the same.

STATEMENT OF GOVERNMENT INTEREST

This invention was made in part with government support under Award No.DE-EE0007312 awarded by the Department of Energy, Office of EnergyEfficiency & Renewable Energy. The United States Government has certainrights in this invention.

BACKGROUND

Technical Field

The present invention generally relates to novel materials exhibitingextremely durable intercalation of lithium, methods for theirmanufacturing, and methods of their use, for example for energy storageapplications. The novel materials comprise a porous scaffold, forexample a carbon exhibiting a pore volume comprising micropores,mesopores, and/or macropores, wherein said volume is impregnated withsilicon, in some embodiments, the impregnated silicon is nano-sizedand/or nano-featured. The silicon-impregnated porous scaffold can befurther coated to reduce any remaining surface area, for example, coatedwith carbon or conductive polymer. Such silicon-impregnated carbonmaterials and carbon- or conductive polymer-coated silicon-impregnatedcarbon materials exhibit remarkable durability with respect to theirintercalation of lithium. Accordingly, the materials disclosed haveutility either alone or in combination with other materials, forexample, combined with carbon particles, binders, or other components toprovide a composition of matter for energy storage applications. Saidenergy storage applications include employing the materials herein aselectrode materials, particularly anode materials, for lithium ionbatteries and related energy storage device employing lithium or lithiumions, for instance lithium air batteries. In certain embodiments, thematerials disclosed herein have utility as anode materials for energystorage devices such as lithium ion batteries and related energy storagedevice employing lithium or lithium ions. Thus, the present inventionalso relates to compositions and devices containing such materials andmethods related to the same.

Description of the Related Art

Lithium-based electrical storage devices have potential to replacedevices currently used in any number of applications. For example,current lead acid automobile batteries are not adequate for nextgeneration all-electric and hybrid electric vehicles due toirreversible, stable sulfate formations during discharge. Lithium ionbatteries are a viable alternative to the lead-based systems currentlyused due to their capacity, and other considerations. Carbon is one ofthe primary materials used in both lithium secondary batteries andhybrid lithium-ion capacitors (LIC). The carbon anode typically storeslithium in between layered graphite sheets through a mechanism calledintercalation. Traditional lithium ion batteries are comprised of agraphitic carbon anode and a metal oxide cathode; however such graphiticanodes typically suffer from low power performance and limited capacity.

Silicon, tin, and other lithium alloying electrochemical modifiers havealso been proposed based on their ability to store very large amounts oflithium per unit weight. However, these materials are fundamentallylimited by the substantial swelling that occurs when they are fullyintercalated with lithium. This swelling and shrinkage when the lithiumis removed results in an electrode that has limited cycle life and lowpower. The solution thus far has been to use very small amounts ofalloying electrochemical modifier in a largely carbon electrode, butthis approach does not impart the desired increase in lithium capacity.Finding a way to increase the alloying electrochemical modifier contentin an anode composition while maintaining cycle stability is desired toincrease capacity. A number of approaches have been utilized involvingnano-structured alloying electrochemical modifier, blends of carbon withalloying electrochemical modifier, or deposition of alloyingelectrochemical modifier onto carbon using vacuum or high temperature.However none of these processes has proven to combine a scalable processthat results in the desired properties.

The aforementioned swelling associated with certain materials, forexample silicon materials, upon their intercalation of lithium is acritical factor in the stability, i.e., cycle life of said materialswith regards to their application for energy storage and distribution,for example, use in rechargeable batteries. Over many cycles, thecapacity of said materials is susceptible to fading. This capacity fademay be precipitated by a variety of different mechanisms, and one of thecritical mechanisms thus described related to the formation of asolid-electrolyte interphase (SEI) in the negative electrode, withcompetes with reversible lithium intercalation. It is known in the artthat SEI is a critical component of capacity fade as the canonicaldegradation mechanism, which can be modeled over long times, based onaccelerated aging for short times and elevated temperatures.

It is described in the art that SEI layer plays an important role in thesafety, power capability, and cyclic life of Li-ion batteries. It isalso described that formation of a chemically and mechanically stableSEI layer is important for improving the cycle life of lithium-ionbatteries. The SEI layer on silicon in an anode forms due to reductionof organic solvents and anions at the electrode surface during chargingand discharging cycles of batteries, with a substantial degree of theformation happening during the first cycle. Furthermore, certainelectrolyte additives, such as vinylene carbonate, propylene carbonate,lithium difluoro-oxalatoborate, and fluoro-ethylene carbonate, and otherspecies known in the art, and combinations thereof, can dramaticallyimprove the cyclic efficiency of silicon-based anodes. SEI layers cancomprise fluorinated carbon and silicon species, besides the usualLi₂CO₃, alkyl Li carbonates (ROCO₂Li) (lithium carboxylate), LiF, ROLi(lithium alkoxide), and polyethylene oxides that are found on graphiteelectrodes. SEI formation on the negative electrode is an irreversiblereaction that consumes cyclable Li-ions from the positive electrodeleading to most of the capacity loss observed in the firstlithiation/delithiation cycle of secondary lithium-ion batteries.Besides capacity loss in the first cycle, continuous formation of thislayer also increases resistance to Li-ion diffusion (i.e., internalimpedance of a battery).

The repeated expansion and contraction of silicon-based anode materialsleads to instability of SEI, for example, cracking and reformation,concomitantly contributing to the capacity fade of the anode. To thisend, the art describes a variety of different silicon size andgeometries that are preferred in order to avert fracture and mitigatethe propensity for chemical and mechanical degradation that can occurupon cycling in a lithium-ion battery. To this end, the art (RSCAdvances, 2013, 3, 7398, “Critical silicon-anode size for avertinglithiation-induced mechanical failure of lithium-ion batteries, Ma etal.) describes 90 nm as a critical size for nanoparticles, 70 nm fornanowires, and 33 nm for nanofilms, below these dimensions (for theirrespective geometries) the silicon nanostructures remain undamaged uponlithiation. Another report in the art (DOI: 10.1002/anie.200906287, “ACritical Size of Silicon Nano-Anodes for Lithium RechargeableBatteries,” Angewandte Chemie, Vol 49, Iss. 12, pp 2146-2149, 2010, Kimet al.) describes for well-dispersed silicon nanocrystals that anapproximate size of 10 nm showed higher capacity retention compared to 5nm or 20 nm sizes.

Additionally, nano features are important to both prevent pulverizationof silicon during expansion and contraction as well as retain anamorphous structure throughout cycling. Pulverization is identified as amechanical failure of silicon due to extreme strain gradients throughthe bulk structure. As silicon is lithiated, it will expand in volume(upwards to 300%). Lithium ions move very slowly through solid silicon.During lithium insertion, a silicon particle may hold large amounts oflithium near the surface and none in the center of the particle. Theconcentration gradient creates a non-uniform expansion through the crosssection. The extreme surface volume expansion will cause the siliconparticle to tear apart away from the inside, cracking and fracturing.Once silicon has pulverized the cell will fail, as there is no knownmethod to salvage the performance.

Accordingly, for energy storage applications, the preferred silicon sizeis less than 1 micron, preferable less than 800 nm, preferably less than300 nm, preferably less than 150 nm, preferably less than 100 nm,preferably less than 90 nm, preferably less than 70 nm, preferably lessthan 50 nm, preferably less than 33 nm, preferably less than 20 nm. Incertain instances, the preferred silicon size is between 5 and 20 nm. Inspecific instances, the preferred silicon size is less than 90 nm for ananoparticle. In specific instances, the preferred silicon size is lessthan 70 nm for a nanowire. In specific instances, the preferred siliconsize is less than 33 nm for a nanofilm.

A silicon particle of the dimensions described above is generallyreferred to as a nano-sized silicon particle. The particle size istypically described as the Dv,50 or silicon particle size at 50% of thevolume distribution, as measured by various methods known in the art,for instance by laser diffraction particle sizing techniques.

Alternatively, or in addition the silicon exhibiting a primary particlesize in the ranges described above, the silicon particle can alsoexhibit nano features. The silicon nano-features preferably comprise anano feature size less than 1 micron, preferably less than 300 nm,preferably less than 150 nm, preferably less than 100 um, preferablyless than 50 nm, preferably less than 30 nm, preferably less than 15 nm.A silicon particle with the features described above is generallyreferred to as a silicon particle with nano-sized features. Thenano-sized features can be discerned by various methods known in theart, for instance by scanning electron microscopy.

Current technologies for achieving nano sized silicons are expensive anddifficult to scale. For instance, the first commonly recognizedsuccessful production of Si nanoclusters was reported by Heath andco-workers (Science 1992, 258, 1131; P. E. Batson, J. R. Heath, Phys.Rev. Lett. 1993, 71, 911), and involved the reduction of SiCl4 at hightemperature and high pressure in a bomb fitted into a heating mantle. Inanother example, a process utilized SiCl4 reduction at room temperatureunder an inert atmosphere, however the product obtained at roomtemperature was not fully crystallized, requiring further hightemperature annealing. Similar solution syntheses have been reported atlow or high temperature after reducing silicon salts with LiAlH4 oralkyl silanes, however, all such methods produce a broad particle sizedistribution or involve aggregation of the nanoparticles. Furthermore,these approaches are not suitable for enabling commercial utility; thescalability and material yields are insufficient to allow for their usein anode production for lithium secondary batteries.

Therefore, the need remains in the art for easily scalable, inexpensive,and improved processes for producing porous silicon materials comprisingnano-sized particles and/or exhibiting nano-features that, uponcombination with a suitable hard carbon material, can generate thedesired electrochemical properties. The current invention meets thisneed, and provides further related advantages.

BRIEF SUMMARY

In general terms, the current invention is directed to compositematerials wherein silicon is deposited into the pore volume of a porousscaffold material. The porous scaffold material can comprise a varietyof different materials. In certain preferred embodiments, the porousscaffold material is porous carbon material comprising micropore,mesopore, and/or macropores. Specifically, the porous carbon materialprovides pores in the range of 5 to 1000 nm, which are subsequentlyfilled with silicon. Accordingly, this disclosure also concerns methodsfor manufacturing composite materials wherein silicon is deposited intothe pore volume of a porous scaffold material. These composites exhibitremarkably durable intercalation of lithium, and therefore provideoptimized lithium storage and utilization properties. These novelcomposites find utility in any number of electrical energy storagedevices, for example as electrode material in lithium-based electricalenergy storage devices (e.g., lithium ion batteries). Electrodescomprising the novel composites disclosed herein display high reversiblecapacity, high first cycle efficiency, high power performance or anycombination thereof. The present inventors have discovered that suchimproved electrochemical performance is related to the size of thesilicon, the integrity of the silicon and carbon material duringcycling, formation of a stable SEI layer, the physicochemical propertiesof the scaffold materials, for example the surface area and pore volumecharacteristics of the carbon scaffold, and other properties, as well asthe approaches used to manufacture and compound the materials.

Accordingly, in one embodiment, the present disclosure provides for themanufacturing of a novel composite material with durable intercalationof lithium, wherein the composite comprises a porous scaffold andsilicon. For example, the process may involve the following steps:

-   -   a) Creation of a porous scaffold material, wherein the said        porous scaffold material comprises a pore volume in the range of        5 to 1000 nm,    -   b) Impregnation of silicon within the porous scaffold material,        resulting in a silicon-impregnated carbon material

Accordingly, in one embodiment, the present disclosure provides for themanufacturing of a novel composite material with durable intercalationof lithium, wherein the composite comprises carbon and silicon. Forexample, the process may involve the following steps:

-   -   a) mixing polymer(s) and/or polymer precursor(s) and storing for        a period of time at sufficient temperature to allow for        polymerization of the precursors,    -   b) carbonization of the resulting polymer material to create a        porous carbon material    -   c) subjecting the porous carbon material to elevated temperature        in the presence of a silicon-containing gas, resulting in a        silicon-impregnated carbon material

Accordingly, in one embodiment, the present disclosure provides for themanufacturing of a novel composite material with durable intercalationof lithium, wherein the composite comprises a layer of carbonsurrounding the silicon-impregnated carbon material. For example, theprocess may involve the following steps:

-   -   a) mixing polymer(s) and/or polymer precursor(s) and storing for        a period of time at sufficient temperature to allow for        polymerization of the precursors,    -   b) carbonization of the resulting polymer material to create a        porous carbon material    -   c) subjecting the porous carbon material to elevated temperature        in the presence of a silicon-containing gas, resulting in a        silicon-impregnated carbon material    -   d) applying a carbon layer on the silicon-impregnated carbon        material to yield a carbon-coated, silicon-impregnated carbon        material

Accordingly, in one embodiment, the present disclosure provides for themanufacturing of a novel composite material with durable intercalationof lithium, wherein the composite comprises a layer of conductivepolymer surrounding the silicon-impregnated carbon material. Forexample, the process may involve the following steps:

-   -   a) mixing polymer(s) and/or polymer precursor(s) and storing for        a period of time at sufficient temperature to allow for        polymerization of the precursors,    -   b) carbonization of the resulting polymer material to create a        porous carbon material    -   c) subjecting the porous carbon material to elevated temperature        in the presence of a silicon-containing gas, resulting in a        silicon-impregnated carbon material    -   d) applying conductive polymer around the silicon-impregnated        carbon material to yield a silicon-impregnated carbon material        further embedded within a conductive polymer network

Accordingly, in one embodiment, the present disclosure provides for themanufacturing of a novel composite material with durable intercalationof lithium, wherein the composite comprises a layer of conductivepolymer surrounding a carbon-coated, silicon-impregnated carbonmaterial. For example, the process may involve the following steps:

-   -   a) mixing polymer(s) and/or polymer precursor(s) and storing for        a period of time at sufficient temperature to allow for        polymerization of the precursors,    -   b) carbonization of the resulting polymer material to create a        porous carbon material    -   c) subjecting the porous carbon material to elevated temperature        in the presence of a silicon-containing gas, resulting in a        silicon-impregnated carbon material    -   d) applying a carbon layer on the silicon-impregnated carbon        material to yield a carbon-coated, silicon-impregnated carbon        material    -   e) applying conductive polymer around the carbon-coated,        silicon-impregnated carbon material to yield a carbon-coated,        silicon-impregnated carbon material further embedded within a        conductive polymer network. The conductive polymer can be        optionally subject to pyrolysis.

In other embodiments is provided a composite comprising a porous carbonscaffold and silicon, wherein the composite comprises from 15 to 85%silicon by weight, and wherein the composite has a pore structurecomprising less than 10% micropores, greater than 30% mesopores, greaterthan 30% macropores and a total pore volume less than 0.5 cm³/g, asdetermined by nitrogen sorption.

In other embodiments is provided a composite comprising a porous carbonscaffold and silicon, wherein the composite comprises from 15 to 85%silicon by weight, and wherein, the porous carbon scaffold has a porestructure comprising less than 10% micropores, greater than 30%mesopores, greater than 30% macropores and a total pore volume less than0.5 cm³/g, as determined by nitrogen sorption.

In more embodiments is provided a composite comprising a porous carbonscaffold and silicon, wherein the composite comprises from 35 to 65%silicon by weight, and wherein the composite has a pore structurecomprising less than 20% micropores, greater than 60% mesopores, lessthan 30% macropores and a total pore volume between 0.1 and 0.5 cm³/g,as determined by nitrogen sorption.

In more embodiments is provided a composite comprising a porous carbonscaffold and silicon, wherein the composite comprises from 35 to 65%silicon by weight, and wherein, the porous carbon scaffold has a porestructure comprising less than 20% micropores, greater than 60%mesopores, less than 30% macropores and a total pore volume between 0.1and 0.5 cm³/g, as determined by nitrogen sorption.

Accordingly, the present disclosure provides both novel compositions ofmatter in addition to manufacturing methods thereof, wherein saidmaterials exhibit remarkably durable intercalation of lithium whenincorporated into an electrode of a lithium based energy storage device.In some embodiments, the lithium based electrical energy storage deviceis a lithium ion battery or lithium ion capacitor.

These and other aspects of the invention will be apparent upon referenceto the following detailed description. To this end, various referencesare set forth herein which describe in more detail certain backgroundinformation, procedures, compounds and/or compositions, and are eachhereby incorporated by reference in their entirety.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1. Schematic of process to achieve composite particle viamicrowave-enabled silicon deposition on a microwave-absorbing porouscarbon scaffold.

FIG. 2. Pore volume distribution for microporous carbon scaffold andsilicon-containing composites derived from same.

FIG. 3. Pore volume distribution for mixed micro-, meso-, andmacroporous carbon scaffold and silicon-containing composites derivedfrom same.

FIG. 4. Pore volume distribution for macroporous carbon scaffold andsilicon-containing composites derived from same.

FIG. 5. Pore volume distribution for microporous carbon before and afterCVD treatment to cap off micropores.

FIG. 6. Data for anode expansion vs. the gravimetric capacity for barecarbon vs carbon-composited nanosilicon.

FIG. 7. Anode expansion vs. gravimetric capacity data for sample carbonsilicon composites.

FIG. 8. Anode expansion vs. volumetric capacity data for sample carbonsilicon composites.

FIG. 9. Full cell data for Wh/L relative to graphite for varioussamples.

FIG. 10. Pore volume distribution for mixed micro and mesoporous carbonscaffold and silicon-containing composites derived from same.

FIG. 11. Capacity retention (filled symbols) and Coulombic efficiency(dashed lines) for silicon carbon composites produced from mixed micro-and mesoporous carbon scaffolds produced at different pyrolysistemperatures (PC).

FIG. 12A-D. Effect of carbon coating of silicon carbon composites. Datashown represent non-coated (striped bars) vs coated (solid bars) samplesmeasured electrochemically in half cells: (12A) average calculatedsilicon capacity (mAh/g), (12B) average observed composite capacity(mAh/g), (12C) average Coulombic efficiency, and (12D) average capacityretention at cycle 20.

FIG. 13. Anode expansion vs. volumetric capacity at full lithiation forvarious carbon silicon composites.

FIG. 14. Full cell cycling stability for silicon carbon compositesproduced from relatively smaller (triangles) vs larger (diamonds) sizedporous carbon scaffolds.

FIG. 15. Full cell cycling stability for silicon carbon compositesproduced from porous carbon scaffolds that were carbon-coated(triangles) vs non-carbon-coated (diamonds).

FIG. 16. Capacity retention for full cell, pouch cell cycling ofC-coated silicon carbon composites according to Example 29.

FIG. 17. Gravimetric capacity for full cell, pouch cell cycling ofC-coated silicon carbon composites according to Example 29.

FIG. 18. Extraction capacity at various cycling rates for variousmaterials according to Example 30.

FIG. 19. Percent of maximum extraction capacity at various cycling ratesfor various materials according to Example 30.

FIG. 20. Cycle stability at various extent of anode densification fornovel silicon carbon composite according to Example 31.

FIG. 21. Cycle stability at various extent of anode densification forsilicon oxide comparator according to Example 31.

FIG. 22. Full cell cycling stability for silicon carbon compositesproduced from porous carbon scaffold that was carbon-coated vsnon-carbon-coated according to Example 35.

FIG. 23. Full cell cycling stability for C-coated silicon carboncomposite compared to graphite in full cell, coin cell according toExample 36.

FIG. 24. Differential voltage plot for the anode for the full cellcycling stability for C-coated silicon carbon composite compared tographite in full cell, coin cell according to Example 36.

FIG. 25. Differential voltage plot for the cathode for the full cellcycling stability for C-coated silicon carbon composite compared tographite in full cell, coin cell according to Example 36.

FIG. 26. Determination of particle expansion for silicon carboncomposite by in-situ TEM according to Example 39.

FIG. 27. Determination of particle expansion for carbon-coated siliconcarbon composite by in-situ TEM according to Example 39.

DETAILED DESCRIPTION

In the following description, certain specific details are set forth inorder to provide a thorough understanding of various embodiments.However, one skilled in the art will understand that the invention maybe practiced without these details. In other instances, well-knownstructures have not been shown or described in detail to avoidunnecessarily obscuring descriptions of the embodiments. Unless thecontext requires otherwise, throughout the specification and claimswhich follow, the word “comprise” and variations thereof, such as,“comprises” and “comprising” are to be construed in an open, inclusivesense, that is, as “including, but not limited to.” Further, headingsprovided herein are for convenience only and do not interpret the scopeor meaning of the claimed invention.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the embodiment is included in at least oneembodiment. Thus, the appearances of the phrases “in one embodiment” or“in an embodiment” in various places throughout this specification arenot necessarily all referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics may be combined inany suitable manner in one or more embodiments. Also, as used in thisspecification and the appended claims, the singular forms “a,” “an,” and“the” include plural referents unless the content clearly dictatesotherwise. It should also be noted that the term “or” is generallyemployed in its sense including “and/or” unless the content clearlydictates otherwise.

DEFINITIONS

As used herein, and unless the context dictates otherwise, the followingterms have the meanings as specified below.

“Energy storage material” refers to a material capable of storingelectrical charge, for example in the form of physically entrainedelectrolytes. Energy storage materials are capable of being charged anddischarged. Examples of energy storage materials include, but are notlimited to, carbon, for example activated carbon, silicon, sulfur,lithium, and combinations thereof. Energy storage materials may be usedin the form of particles, or combinations of inter- and/orintra-particle blends of particles. Energy storage particles can beassembled into electrodes employing dry processing or aqueous ornon-aqueous slurry processing as described in the art.

“Carbon material” refers to a material or substance comprisingsubstantially of carbon. Examples of carbon materials include, but arenot limited to, activated carbon, pyrolyzed carbon, hard carbon,graphite, and other allotropes of carbon.

“Impurity” or “impurity element” refers to a foreign substance (e.g., achemical element) within a material, which differs from the chemicalcomposition of the base material. For example, an impurity in a carbonmaterial refers to any element or combination of elements, other thancarbon, which is present in the carbon material. Impurity levels aretypically expressed in parts per million (ppm).

“TXRF impurity” is any impurity element as detected by total x-rayfluorescence (TXRF). The phrases “total TXRF impurity content” and“total TXRF impurity level” both refer to the sum of all TXRF impuritiespresent in a sample, for example, a polymer gel or a carbon material, ora silicon material, or a composite material comprising carbon andsilicon.

“Ash content” refers to the nonvolatile inorganic matter that remainsafter subjecting a substance to a high decomposition temperature.Herein, the ash content of a carbon material is calculated from thetotal PUCE impurity content as measured by proton induced x-rayemission, assuming that nonvolatile elements are completely converted toexpected combustion products (i.e., oxides).

“Polymer” refers to a molecule comprising two or more structuralrepeating units.

“Synthetic polymer precursor material” or “polymer precursor” refers tothe compounds used in the preparation of a synthetic polymer. Examplesof polymer precursors that can be used in the preparations disclosedherein include, but are not limited to aldehydes (i.e., HC(═O)R, where Ris an organic group), such as for example, methanal (formaldehyde);ethanal (acetaldehyde); propanal (propionaldehyde); butanal(butyraldehyde); glucose; benzaldehyde and cinnamaldehyde. Otherexemplary polymer precursors include, but are not limited to, phenoliccompounds such as phenol and polyhydroxy benzenes, such as dihydroxy ortrihydroxy benzenes, for example, resorcinol (i.e., 1,3-dihydroxybenzene), catechol, hydroquinone, and phloroglucinol. Mixtures of two ormore polyhydroxy benzenes are also contemplated within the meaning ofpolymer precursor.

“Sol” refers to a colloidal suspension of precursor particles (e.g.,polymer precursors), and the term “gel” refers to a wetthree-dimensional porous network obtained by condensation or reaction ofthe precursor particles.

“Polymer gel” refers to a gel in which the network component is apolymer; generally a polymer gel is a wet (aqueous or non-aqueous based)three-dimensional structure comprising a polymer formed from syntheticprecursors or polymer precursors.

“Sol gel” refers to a sub-class of polymer gel where the polymer is acolloidal suspension that forms a wet three-dimensional porous networkobtained by reaction of the polymer precursors.

“Polymer hydrogel” or “hydrogel” refers to a subclass of polymer gel orgel wherein the solvent for the synthetic precursors or monomers iswater or mixtures of water and one or more water-miscible solvent.

“Acid” refers to any substance that is capable of lowering the pH of asolution. Acids include Arrhenius, Brønsted and Lewis acids. A “solidacid” refers to a dried or granular compound that yields an acidicsolution when dissolved in a solvent. The term “acidic” means having theproperties of an acid.

“Base” refers to any substance that is capable of raising the pH of asolution. Bases include Arrhenius, Brønsted and Lewis bases. A “solidbase” refers to a dried or granular compound that yields basic solutionwhen dissolved in a solvent. The term “basic” means having theproperties of a base.

“Catalyst” is a substance which alters the rate of a chemical reaction.Catalysts participate in a reaction in a cyclic fashion such that thecatalyst is cyclically regenerated. The present disclosure contemplatescatalysts which are sodium free. The catalyst used in the preparation ofa polymer gel as described herein can be any compound that facilitatesthe polymerization of the polymer precursors to form a polymer gel. A“volatile catalyst” is a catalyst which has a tendency to vaporize at orbelow atmospheric pressure. Exemplary volatile catalysts include, butare not limited to, ammoniums salts, such as ammonium bicarbonate,ammonium carbonate, ammonium hydroxide, and combinations thereof.

“Carbonizing”, “pyrolyzing”, “carbonization” and “pyrolysis” each referto the process of heating a carbon-containing substance at a pyrolysisdwell temperature in an inert atmosphere (e.g., argon or nitrogen) or ina vacuum such that the targeted material collected at the end of theprocess is primarily carbon. “Pyrolyzed” refers to a material orsubstance, for example a carbon material, which has undergone theprocess of pyrolysis.

“Density” as used with respect to an electrode, refers to the totaldensity of the active material (e.g., carbon-silicon composite) and anyoptional binder, conductivity enhancer and the like. The density of anelectrode does not include the mass or volume associate with a currentcollector associate with the electrode.

“Dwell temperature” refers to the temperature of the furnace during theportion of a process which is reserved for maintaining a relativelyconstant temperature (i.e., neither increasing nor decreasing thetemperature). For example, the pyrolysis dwell temperature refers to therelatively constant temperature of the furnace during pyrolysis, and theactivation dwell temperature refers to the relatively constanttemperature of the furnace during activation.

“Pore” refers to an opening or depression in the surface, or a tunnel ina carbon material, such as for example activated carbon, pyrolyzed driedpolymer gels, pyrolyzed polymer cryogels, pyrolyzed polymer xerogels,pyrolyzed polymer aerogels, activated dried polymer gels, activatedpolymer cryogels, activated polymer xerogels, activated polymer aerogelsand the like. A pore can be a single tunnel or connected to othertunnels in a continuous network throughout the structure.

“Pore structure” refers to the layout of the surface of the internalpores within a carbon material, such as an activated carbon material.Components of the pore structure include pore size, pore volume, surfacearea, density, pore size distribution, and pore length. Generally thepore structure of activated carbon material comprises micropores andmesopores.

“Mesopore” generally refers to pores having a diameter between about 2nanometers and about 50 nanometers while the term “micropore” refers topores having a diameter less than about 2 nanometers. Mesoporous carbonmaterials comprise greater than 50% of their total pore volume inmesopores while microporous carbon materials comprise greater than 50%of their total pore volume in micropores. Pores larger than about 50nanometers are referred to as “macropores”.

“Surface area” refers to the total specific surface area of a substancemeasurable by the BET technique. Surface area is typically expressed inunits of m²/g. The BET (Brunauer/Emmett/Teller) technique employs aninert gas, for example nitrogen, to measure the amount of gas adsorbedon a material and is commonly used in the art to determine theaccessible surface area of materials.

“Connected” when used in reference to mesopores and micropores refers tothe spatial orientation of such pores.

“Binder” refers to a material capable of holding individual particles ofcarbon together such that after mixing a binder and carbon together theresulting mixture can be formed into sheets, pellets, disks or othershapes. Non-exclusive examples of binders include fluoro polymers, suchas, for example, PTFE (polytetrafluoroethylene, Teflon), PFA(perfluoroalkoxy polymer resin, also known as Teflon), FEP (fluorinatedethylene propylene, also known as Teflon), ETFE(polyethylenetetrafluoroethylene, sold as Tefzel and Fluon), PVF(polyvinyl fluoride, sold as Tedlar), ECTFE(polyethylenechlorotrifluoroethylene, sold as Halar), PVDF(polyvinylidene fluoride, sold as Kynar), PCTFE(polychlorotrifluoroethylene, sold as Kel-F and CTFE), trifluoroethanoland combinations thereof.

“Composite material” refers to a composition comprising multiple (i.e.,2 or more) distinct, chemical species within the same particle, forexample particles that comprise both porous carbon materials and siliconmaterials.

“Allotrope” refers to a material which can exists in different forms.C60, graphene, diamond, hard carbon, soft carbon, graphite, and carbonnanotubes are all examples of carbon allotropes. “Hard Carbon” refers toa non-graphitizable carbon material. At elevated temperatures(e.g., >1500° C.) a hard carbon remains substantially amorphous, whereasa “soft” carbon will undergo crystallization and become graphitic.

“Lithium uptake” refers to a carbon's ability to intercalate, absorb, orstore lithium as measured as a ratio between the maximum number oflithium atoms to 6 carbon atoms.

“SEI,” as known in the art, refers to solvent-electrolyte interphase.

“Young's modulus,” also known as the tensile modulus or elastic modulus,is a mechanical property of linear elastic solid materials. It measuresthe force (per unit area) that is needed to stretch (or compress) amaterial.

“Bulk modulus,” describes volumetric elasticity, or the tendency of anobject to deform in all directions when uniformly loaded in alldirections; it is defined as volumetric stress over volumetric strain,and is the inverse of compressibility. The bulk modulus is an extensionof Young's modulus to three dimensions.

“Coulombic efficiency,” herein refers to the amount of capacitivedischarge achieved as a result of lithium extraction from the anode of alithium ion based energy storage device divided by the amount ofcapacitive charge or uptake achieved as a result of lithium insertion.Coulombic efficiency is reported as a percentage, or as a fraction(e.g., 99%=0.99).

“Nano-sized” means the material (e.g., silicon) has at least onedimension on the order of nanometers, for example at least one dimensionless than 1 micron. For energy storage applications, the preferredsilicon size is less than 1 micron, preferable less than 800 nm,preferably less than 300 nm, preferably less than 150 nm, preferablyless than 100 nm, preferably less than 50 nm, preferably less than 30nm, preferably less than 15 nm. A silicon particle of the dimensionsdescribed above is generally referred to as a nano-sized siliconparticle. The particle size is typically described as the Dv,50 orsilicon particle size at 50% of the volume distribution, as measured byvarious methods known in the art, for instance by laser diffractionparticle sizing techniques.

Alternatively, or in addition the silicon exhibiting a primary particlesize in the ranges described above, the silicon particle can alsoexhibit nano features. “Nanofeatures” refer to features, such as poresand the like, having a dimension on the order of nanometers, for exampleless than 1 micron. A “nano-featured” material is one which comprisesnanofeatures. The silicon nano-features preferably comprise a nanofeature size less than 1 micron, preferably less than 300 nm, preferablyless than 150 nm, preferably less than 100 μm, preferably less than 50nm, preferably less than 30 nm, preferably less than 15 nm. A siliconparticle with the features described above is generally referred to as asilicon particle with nano-sized features. The nano-sized features canbe discerned by various methods known in the art, for instance byscanning electron microscopy.

A. Porous Scaffold Materials

For the purposes of the current invention, a porous scaffold isrequired, into which silicon is to be impregnated. In this context, theporous scaffold can compromise various materials. In preferredembodiments the porous scaffold material primarily comprises carbon, forexample hard carbon. Other allotropes of carbon are also envisioned, forexample, graphite, amorphous carbon, diamond, C60, carbon nanotubes(e.g., single and/or multi-walled), graphene and/or carbon fibers. Theintroduction of porosity into the carbon material can be achieved by avariety of means. For instance, the porosity in the carbon material canbe achieved by modulation of polymer precursors, and/or processingconditions to create said porous carbon material, and described indetail in the subsequent section.

In other embodiments, the porous scaffold can comprise a polymermaterial. To this end, a wide variety of polymers are envisioned to haveutility, including, but not limited to, inorganic polymer, organicpolymers, and addition polymers. Examples of inorganic polymers in thiscontext includes, but are not limited to homochain polymers ofsilicon-silicon such as polysilanes, silicon carbide, polygermanes, andpolystannanes. Additional examples of inorganic polymers includes, butare not limited to, heterochain polymers such as polyborazylenes,polysiloxanes like polydimethylsiloxane (PDMS), polymethylhydrosiloxane(PMHS) and polydiphenylsiloxane, polysilazanes likeperhydridopolysilazane (PHPS), polyphosphazenes andpoly(dichlorophosphazenes), polyphosphates, polythiazyls, andpolysulfides. Examples of organic polymers includes, but are not limitedto, low density polyethylene (LDPE), high density polyethylene (HDPE),polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), nylon,nylon 6, nylon 6,6, teflon (Polytetrafluoroethylene), thermoplasticpolyurethanes (TPU), polyureas, poly(lactide), poly(glycolide) andcombinations thereof, phenolic resins, polyamides, polyaramids,polyethylene terephthalate, polychloroprene, polyacrylonitrile,polyaniline, polyimide, poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PDOT:PSS), and others known in the arts. The organic polymercan be synthetic or natural in origin. In some embodiments, the polymeris a polysaccharide, such as starch, cellulose, cellobiose, amylose,amylpectin, gum Arabic, lignin, and the like. In some embodiments, thepolysaccharide is derived from the carmelization of mono- or oligomericsugars, such as fructose, glucose, sucrose, maltose, raffinose, and thelike.

Concomitant with the myriad variety of polymers envisioned with thepotential to provide a porous substrate, various processing approachesare envisioned to achieve said porosity. In this context, generalmethods for imparting porosity into various materials are myriad, asknown in the art, including, but certainly not limited to, methodsinvolving emulsification, micelle creation, gasification, dissolutionfollowed by solvent removal (for example, lyophilization), axialcompaction and sintering, gravity sintering, powder rolling andsintering, isostatic compaction and sintering, metal spraying, metalcoating and sintering, metal injection molding and sintering, and thelike. Other approaches to create a porous polymeric material, includingcreation of a porous gel, such as a freeze dried gel, aerogel, and thelike are also envisioned.

In certain embodiments, the porous scaffold material comprises a porousceramic material. In certain embodiments, the porous scaffold materialcomprises a porous ceramic foam. In this context, general methods forimparting porosity into ceramic materials are varied, as known in theart, including, but certainly not limited to, creation of porous In thiscontext, general methods and materials suitable for comprising theporous ceramic include, but are not limited to, porous aluminum oxide,porous zirconia toughened alumina, porous partially stabilized zirconia,porous alumina, porous sintered silicon carbide, sintered siliconnitride, porous cordierite, porous zirconium oxide, clay-bound siliconcarbide, and the like.

In certain embodiments, the porous scaffold comprises porous silica orother silicon material containing oxygen. The creation of silicon gels,including sol gels, and other porous silica materials is known in theart.

In certain embodiments, the porous material comprises a porous metal.Suitable metals in this regard include, but are not limited to porousaluminum, porous steel, porous nickel, porous Inconcel, porous Hasteloy,porous titanium, porous copper, porous brass, porous gold, poroussilver, porous germanium, and other metals capable of being formed intoporous structures, as known in the art. In some embodiments, the porousscaffold material comprises a porous metal foam. The types of metals andmethods to manufacture related to same are known in the art. Suchmethods include, but are not limited to, casting (including foaming,infiltration, and lost-foam casting), deposition (chemical andphysical), gas-eutectic formation, and powder metallurgy techniques(such as powder sintering, compaction in the presence of a foamingagent, and fiber metallurgy techniques).

B. Porous Carbon Materials

Methods for preparing porous carbon materials from polymer precursorsare known in the art. For example, methods for preparation of carbonmaterials are described in U.S. Pat. Nos. 7,723,262, 8,293,818,8,404,384, 8,654,507, 8,916,296, 9,269,502, U.S. patent application Ser.Nos. 12/965,709 and 13/486,731, and international patent applicationPCT/US2014/029106, the full disclosures of which are hereby incorporatedby reference in their entireties for all purposes. Accordingly, in oneembodiment the present disclosure provides a method for preparing any ofthe carbon materials or polymer gels described above. The carbonmaterials may be synthesized through pyrolysis of either a singleprecursor, for example a saccharide material such as sucrose, fructose,glucose, dextrin, maltodextrin, starch, amylopectin, amylose, lignin,gum Arabic, and other saccharides known in the art, and combinationsthereof. Alternatively, the carbon materials may be synthesized throughpyrolysis of a complex resin, for instance formed using a sol-gel methodusing polymer precursors such as phenol, resorcinol, bisphenol A, urea,melamine, and other suitable compounds known in the art, andcombinations thereof, in a suitable solvent such as water, ethanol,methanol, and other solvents known in the art, and combinations thereof,with cross-linking agents such as formaldehyde, furfural, and othercross-lining agents known in the art, and combinations thereof. Theresin may be acid or basic, and may contain a catalyst. The catalyst maybe volatile or non-volatile. The pyrolysis temperature and dwell timecan vary as known in the art.

In some embodiments, the methods comprise preparation of a polymer gelby a sol gel process, condensation process or crosslinking processinvolving monomer precursor(s) and a crosslinking agent, two existingpolymers and a crosslinking agent or a single polymer and a crosslinkingagent, followed by pyrolysis of the polymer gel. The polymer gel may bedried (e.g., freeze dried) prior to pyrolysis; however drying is notnecessarily required.

In some embodiments, the polymer gel is freeze dried, or lyophilized, inorder to leave porosity of the desired extent and nature, for example,macroporosity. Without being bound by theory, the porosity in thelyophilized gel, or cryogel. In some embodiments, the gel in freezedried by first reducing the size of monolithic material into particles,then extremely rapid freezing, the drying under vacuum, in order toachieve a cryogel. The particle size reduction can be accomplished byvarious methods as known in the art, for example by crushing, grinding,milling by various means, and the like. Such methods are suitable tocreate particles with a volume average particle (Dv,50) of less than a10 cm, for example less than 5 cm, for example less than 2 cm, forexample less than 1 cm, for example less than 5 mm, for example lessthan 1 mm, for example less than 100 microns, for example less than 10microns. The extremely rapid freezing can be accomplished by subjectingthe particles to extremely cold liquid, for example liquid nitrogen, orotherwise rapidly frozen as known in the art. Without being bound bytheory, the extremely rapid freezing creates a large extent of icesurface area, and, upon sublimation under vacuum as known in the art,results in a large surface area in the freeze dried polymer, or cryogel.

The sol gel process provides significant flexibility for incorporationof various electrochemical modifiers, which can be incorporated at anynumber of steps. In one embodiment, a method for preparing a polymer gelcomprising an electrochemical modifier is provided. In anotherembodiment, methods for preparing pyrolyzed polymer gels are provided.Details of the variable process parameters of the various embodiments ofthe disclosed methods are described below.

The target carbon properties can be derived from a variety of polymerchemistries provided the polymerization reaction produces aresin/polymer with the necessary carbon backbone. Different polymerfamilies include novolacs, resoles, acrylates, styrenics, ureathanes,rubbers (neoprenes, styrene-butadienes, etc.), nylons, etc. Thepreparation of any of these polymer resins can occur via a number ofdifferent processes including sol gel, emulsion/suspension, solid state,solution state, melt state, etc., for either polymerization andcrosslinking processes.

The polymer gel may be prepared by a sol gel process. For example, thepolymer gel may be prepared by co-polymerizing one or more polymerprecursors in an appropriate solvent. In one embodiment, the one or morepolymer precursors are copolymerized under acidic conditions. In someembodiments, a first polymer precursor is a phenolic compound and asecond polymer precursor is an aldehyde compound. In one embodiment, ofthe method the phenolic compound is phenol, resorcinol, catechol,hydroquinone, phloroglucinol, or a combination thereof; and the aldehydecompound is formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde,benzaldehyde, cinnamaldehyde, or a combination thereof. In a furtherembodiment, the phenolic compound is resorcinol, phenol or a combinationthereof, and the aldehyde compound is formaldehyde. In yet furtherembodiments, the phenolic compound is resorcinol and the aldehydecompound is formaldehyde. Other polymer precursors include nitrogencontaining compounds such as melamine, urea and ammonia.

In some embodiments an electrochemical modifier is incorporated into thematerial as polymer. For example, the organic or carbon containingpolymer, RF for example, is copolymerized with the polymer, whichcontains the electrochemical modifier. In one embodiment, theelectrochemical modifier-containing polymer contains silicon. In oneembodiment the polymer is tetraethylorthosiliane (TEOS). In oneembodiment, a TEOS solution is added to the RF solution prior to orduring polymerization. In another embodiment the polymer is a polysilanewith organic side groups. In some cases these side groups are methylgroups, in other cases these groups are phenyl groups, in other casesthe side chains include phenyl, pyrol, acetate, vinyl, siloxanefragments. In some cases the side chain includes a group 14 element(silicon, germanium, tin or lead). In other cases the side chainincludes a group 13 element (boron, aluminum, boron, gallium, indium).In other cases the side chain includes a group 15 element (nitrogen,phosphorous, arsenic). In other cases the side chain includes a group 16element (oxygen, sulfur, selenium). In another embodiment theelectrochemical modifier is a silole. In some cases it is aphenol-silole or a silafluorene. In other cases it is a poly-silole or apoly-silafluorene. In some cases the silicon is replaced with germanium(germole or germafluorene), tin (stannole or stannaflourene) nitrogen(carbazole) or phosphorous (phosphole, phosphafluorene). In all casesthe heteroatom containing material can be a small molecule, an oligomeror a polymer. Phosphorous atoms may or may not be also bonded to oxygen.

In some embodiments the reactant contains phosphorous. In certain otherembodiments, the phosphorus is in the form of phosphoric acid. Incertain other embodiments, the phosphorus can be in the form of a salt,wherein the anion of the salt comprises one or more phosphate,phosphite, phosphide, hydrogen phosphate, dihydrogen phosphate,hexafluorophosphate, hypophosphite, polyphosphate, or pyrophosphateions, or combinations thereof. In certain other embodiments, thephosphorus can be in the form of a salt, wherein the cation of the saltcomprises one or more phosphonium ions. The non-phosphate containinganion or cation pair for any of the above embodiments can be chosen forthose known and described in the art. In the context, exemplary cationsto pair with phosphate-containing anions include, but are not limitedto, ammonium, tetraethylammonium, and tetramethylammonium ions. In thecontext, exemplary anions to pair with phosphate-containing cationsinclude, but are not limited to, carbonate, dicarbonate, and acetateions.

In some cases the crosslinker is important because of its chemical andelectrochemical properties. In other cases the crosslinker is importantbecause it locks in the polymer geometry. In other cases both polymergeometry and chemical composition are important.

The crosslinker can react at either low or high temperatures. In somecases a portion of the reaction will occur at low temperatures with therest of the reaction occurring at higher temperatures. Both extent ofcrosslinking and reaction kinetics can be measured by a variety ofchemical techniques (TGA, FTIR, NMR, XRD, etc.) and physical techniques(indentation, tensile testing, modulus, hardness, etc.).

In some cases it will be favorable to have the electrochemical modifierand/or crosslinker evenly distributed throughout the initialco-polymer—a homogenous mixture. In other cases it is important to havean uneven distribution of crosslinker and/or electrochemical modifiedthroughout the initial co-polymer.

The structure of the polymer precursors is not particularly limited,provided that the polymer precursor is capable of reacting with anotherpolymer precursor or with a second polymer precursor to form a polymer.In some embodiments the polymer precursors are selected from an alcohol,a phenol, a polyalcohol, a sugar, an alkyl amine, an aromatic amine, analdehyde, a ketone, a carboxylic acid, an ester, a urea, an acid halide,an alkene, an alkyne, an acrylate, an epoxide and an isocyanate.

Various monomers, molecular components, oligomers and polymericmaterials may be combined to make a variety of polymers including,novolacs, resoles, novolac epoxides (comprised of one or more of phenol,resorcinol, formaldehyde, epichlorohydrin, bisphenol-A, bisphenol-F,epoxide), rubbers (isoprene, styrene-butadiene,styrene-butadiene-styrene, isobutylene, polyacrylate rubber,ethylenene-acrylate rubber, bromo-isobutylene, isoprene, polybutadiene,chloro isobutadiene isoprene, polychloroprene, epichlorohydrin, ethylenepropylene, ethylene propylene diene monomer, polyether urethane,perfluorocarbon rubber, fluorosilicone, hydrogenated nitrile butadiene,acrylonitrile butadiene, polyurethane), nylons (including nylon-6;nylon-6,6; nylon-6,9; nylon-6,10; nylon-6,12; nylon-11, nylon-12; andnylon-4,6), acrylates (methylacrylate, ethyl acrylate,2-Chloroethyl-vinyl ether, 2-Ethylehexyl acrylate, hydroyethylmethacrylate, butyl acrylate, butyl methacrylate, acrylonitrile),polystyrene, and polyurethanes (composed of ethylene glycol, diethyleneglycol, triethylene glycol, tetraethylene glycol, propylene glycol,tripropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol,neopentyl glycol, 1,6-hexanediol, ethanolamine, diethanolamine,methyldiethanolamine, phenyldiethanolamine, glycerol,trimethylolpropane, 1,2,6-hexanetriol, triethanolamine, pentaerythritol,diethyltoluenediamine, dimethylthiotoluenediamine).

In some cases the polymer precursor materials include (a) alcohols,phenolic compounds, and other mono- or polyhydroxy compounds and (b)aldehydes, ketones, and combinations thereof. Representative alcohols inthis context include straight chain and branched, saturated andunsaturated alcohols. Another exemplary phenol compound is bispehnol Aand related bisphenol molecules. Suitable phenolic compounds includepolyhydroxy benzene, such as a dihydroxy or trihydroxy benzene. Anotherexemplary phenol compound is bispehnol A and related bisphenolmolecules. Representative polyhydroxy benzenes include resorcinol (i.e.,1,3-dihydroxy benzene), catechol, hydroquinone, and phloroglucinol.Mixtures of two or more polyhydroxy benzenes can also be used. Phenol(monohydroxy benzene) can also be used. Representative polyhydroxycompounds include sugars, such as glucose, and other polyols, such asmannitol. Aldehydes in this context include: straight chain saturatedaldehydes such as methanal (formaldehyde), ethanal (acetaldehyde),propanal (propionaldehyde), butanal (butyraldehyde), and the like;straight chain unsaturated aldehydes such as ethenone and other ketenes,2-propenal (acrylaldehyde), 2-butenal (crotonaldehyde), 3 butenal, andthe like; branched saturated and unsaturated aldehydes; andaromatic-type aldehydes such as benzaldehyde, salicylaldehyde,hydrocinnamaldehyde, and the like. Suitable ketones include: straightchain saturated ketones such as propanone and 2 butanone, and the like;straight chain unsaturated ketones such as propenone, 2 butenone, and3-butenone (methyl vinyl ketone) and the like; branched saturated andunsaturated ketones; and aromatic-type ketones such as methyl benzylketone (phenylacetone), ethyl benzyl ketone, and the like. The polymerprecursor materials can also be combinations of the precursors describedabove.

In one embodiment, the method comprises use of a first and secondpolymer precursor, and in some embodiments the first or second polymerprecursor is a carbonyl containing compound and the other of the firstor second polymer precursor is an alcohol-containing compound. In someembodiments, a first polymer precursor is a phenolic compound and asecond polymer precursor is an aldehyde compound (e.g., formaldehyde).In one embodiment, of the method the phenolic compound is phenol,resorcinol, catechol, hydroquinone, phloroglucinol, or a combinationthereof; and the aldehyde compound is formaldehyde, acetaldehyde,propionaldehyde, butyraldehyde, benzaldehyde, cinnamaldehyde, or acombination thereof. In a further embodiment, the phenolic compound isresorcinol, phenol or a combination thereof, and the aldehyde compoundis formaldehyde. In yet further embodiments, the phenolic compound isresorcinol and the aldehyde compound is formaldehyde. In someembodiments, the polymer precursors are alcohols and carbonyl compounds(e.g., resorcinol and aldehyde) and they are present in a ratio of about0.5:1.0, respectively.

In some embodiments, one polymer precursor is an alcohol-containingspecies and another polymer precursor is a carbonyl-containing species.The relative amounts of alcohol-containing species (e.g., alcohols,phenolic compounds and mono- or poly-hydroxy compounds or combinationsthereof) reacted with the carbonyl containing species (e.g. aldehydes,ketones or combinations thereof) can vary substantially. In someembodiments, the ratio of alcohol-containing species to aldehyde speciesis selected so that the total moles of reactive alcohol groups in thealcohol-containing species is approximately the same as the total molesof reactive carbonyl groups in the aldehyde species. Similarly, theratio of alcohol-containing species to ketone species may be selected sothat the total moles of reactive alcohol groups in the alcoholcontaining species is approximately the same as the total moles ofreactive carbonyl groups in the ketone species. The same general 1:1molar ratio holds true when the carbonyl-containing species comprises acombination of an aldehyde species and a ketone species.

In other embodiments, the polymer precursor is a urea or anamine-containing compound. For example, in some embodiments the polymerprecursor is urea or melamine. Other embodiments include polymerprecursors selected from isocyanates or other activated carbonylcompounds such as acid halides and the like. Yet other embodimentsemploy phenolic precursors, including but not limited to phenol,resorcinol, and other hydroxy- and aromatic-ring containing molecules.

In some embodiments of the methods described herein, the molar ratio ofphenolic precursor to catalyst is from about 5:1 to about 2000:1 or themolar ratio of phenolic precursor to catalyst is from about 20:1 toabout 200:1. In further embodiments, the molar ratio of phenolicprecursor to catalyst is from about 25:1 to about 100:1. In furtherembodiments, the molar ratio of phenolic precursor to catalyst is fromabout 5:1 to about 10:1. In further embodiments, the molar ratio ofphenolic precursor to catalyst is from about 100:1 to about 5:1.

In one specific embodiment wherein one of the polymer precursors isresorcinol and/or phenol, and another polymer precursor is formaldehyde,the resorcinol and/or phenol to catalyst ratio can be varied to obtainthe desired properties of the resultant polymer gel and carbonmaterials. In some embodiments of the methods described herein, themolar ratio of resorcinol and/or phenol to catalyst is from about 10:1to about 2000:1 or the molar ratio of resorcinol and/or phenol tocatalyst is from about 20:1 to about 200:1. In further embodiments, themolar ratio of resorcinol and/or phenol to catalyst is from about 25:1to about 100:1. In further embodiments, the molar ratio of resorcinoland/or phenol to catalyst is from about 5:1 to about 10:1. In furtherembodiments, the molar ratio of resorcinol and/or phenol to catalyst isfrom about 100:1 to about 5:1.

The total solids content in the solution or suspension prior to polymergel formation can be varied. The weight ratio of resorcinol to water isfrom about 0.05 to 1 to about 0.70 to 1. Alternatively, the ratio ofresorcinol to water is from about 0.15 to 1 to about 0.6 to 1.Alternatively, the ratio of resorcinol to water is from about 0.15 to 1to about 0.35 to 1. Alternatively, the ratio of resorcinol to water isfrom about 0.25 to 1 to about 0.5 to 1. Alternatively, the ratio ofresorcinol to water is from about 0.3 to 1 to about 0.35 to 0.6.

Examples of solvents useful in the preparation of the polymer gelsdisclosed herein include but are not limited to water or alcohols suchas, for example, ethanol, t-butanol, methanol or combinations thereof aswell as aqueous mixtures of the same. Such solvents are useful fordissolution of the polymer precursor materials, for example dissolutionof the phenolic compound. In addition, in some processes such solventsare employed for solvent exchange in the polymer gel (prior to freezingand drying), wherein the solvent from the polymerization of theprecursors, for example, resorcinol and formaldehyde, is exchanged for apure alcohol. In one embodiment of the present application, a polymergel is prepared by a process that does not include solvent exchange.

Suitable catalysts in the preparation of the polymer gels includevolatile basic catalysts that facilitate polymerization of the precursormaterials into a monolithic polymer. The catalyst can also comprisevarious combinations of the catalysts described above. In embodimentscomprising phenolic compounds, or other polymer precursors, suchcatalysts can be used in the range of molar ratios of 5:1 to 200:1phenolic compound:catalyst. For example, in some specific embodimentssuch catalysts can be used in the range of molar ratios of 5:1 to 10:1phenolic compound:catalyst.

In some embodiments, the gel polymerization process is performed undercatalytic conditions. Accordingly, in some embodiments, the methodcomprises admixing a catalyst with the solvent-free mixture. In someembodiments, the catalyst is a solid at room temperature and pressure.

In some embodiments, the catalyst is a liquid at room temperature andpressure. In some embodiments, the catalyst is a liquid at roomtemperature and pressure that does not provide dissolution of one ormore of the other polymer precursors.

In some embodiments, the catalyst comprises a basic volatile catalyst.For example, in one embodiment, the basic volatile catalyst comprisesammonium carbonate, ammonium bicarbonate, ammonium acetate, ammoniumhydroxide, or combinations thereof. In a further embodiment, the basicvolatile catalyst is ammonium carbonate. In another further embodiment,the basic volatile catalyst is ammonium acetate.

The molar ratio of catalyst to polymer precursor (e.g., phenoliccompound) may have an effect on the final properties of the polymer gelas well as the final properties of the carbon materials. Thus, in someembodiments such catalysts are used in the range of molar ratios of 5:1to 2000:1 polymer precursor:catalyst. In some embodiments, suchcatalysts can be used in the range of molar ratios of 10:1 to 400:1polymer precursor:catalyst. For example in other embodiments, suchcatalysts can be used in the range of molar ratios of 5:1 to 100:1polymer precursor:catalyst. For example, in some embodiments the molarratio of catalyst to polymer precursor is about 400:1. In otherembodiments the molar ratio of catalyst to polymer precursor is about100:1. In other embodiments the molar ratio of catalyst to polymerprecursor is about 50:1. In other embodiments the molar ratio ofcatalyst to polymer precursor is about 10:1. In certain of the foregoingembodiments, the polymer precursor is a phenolic compound such asresorcinol or phenol.

In still other embodiments, the method comprises admixing an acid. Incertain embodiments, the acid is a solid at room temperature andpressure. In some embodiments, the acid is a liquid at room temperatureand pressure. In some embodiments, the acid is a liquid at roomtemperature and pressure that does not provide dissolution of one ormore of the other polymer precursors.

The acid may be selected from any number of acids suitable for thepolymerization process. For example, in some embodiments the acid isacetic acid and in other embodiments the acid is oxalic acid. In furtherembodiments, the acid is mixed with the first or second solvent in aratio of acid to solvent of 99:1, 90:10, 75:25, 50:50, 25:75, 20:80,10:90 or 1:90. In other embodiments, the acid is acetic acid and thefirst or second solvent is water. In other embodiments, acidity isprovided by adding a solid acid.

The total content of acid in the mixture can be varied to alter theproperties of the final product. In some embodiments, the acid ispresent from about 1% to about 50% by weight of mixture. In otherembodiments, the acid is present from about 5% to about 25%. In otherembodiments, the acid is present from about 10% to about 20%, forexample about 10%, about 15% or about 20%.

In certain embodiments, the polymer precursor components are blendedtogether and subsequently held for a time and at a temperaturesufficient to achieve polymerization. One or more of the polymerprecursor components can have particle size less than about 20 mm insize, for example less than 10 mm, for example less than 7 mm, forexample, less than 5 mm, for example less than 2 mm, for example lessthan 1 mm, for example less than 100 microns, for example less than 10microns. In some embodiments, the particle size of one or more of thepolymer precursor components is reduced during the blending process.

The blending of one or more polymer precursor components in the absenceof solvent can be accomplished by methods described in the art, forexample ball milling, jet milling, Fritsch milling, planetary mixing,and other mixing methodologies for mixing or blending solid particleswhile controlling the process conditions (e.g., temperature). The mixingor blending process can be accomplished before, during, and/or after (orcombinations thereof) incubation at the reaction temperature.

Reaction parameters include aging the blended mixture at a temperatureand for a time sufficient for the one or more polymer precursors toreact with each other and form a polymer. In this respect, suitableaging temperature ranges from about room temperature to temperatures ator near the melting point of one or more of the polymer precursors. Insome embodiments, suitable aging temperature ranges from about roomtemperature to temperatures at or near the glass transition temperatureof one or more of the polymer precursors. For example, in someembodiments the solvent free mixture is aged at temperatures from about20° C. to about 600° C., for example about 20° C. to about 500° C., forexample about 20° C. to about 400° C., for example about 20° C. to about300° C., for example about 20° C. to about 200° C. In certainembodiments, the solvent free mixture is aged at temperatures from about50 to about 250° C.

The reaction duration is generally sufficient to allow the polymerprecursors to react and form a polymer, for example the mixture may beaged anywhere from 1 hour to 48 hours, or more or less depending on thedesired result. Typical embodiments include aging for a period of timeranging from about 2 hours to about 48 hours, for example in someembodiments aging comprises about 12 hours and in other embodimentsaging comprises about 4-8 hours (e.g., about 6 hours).

In certain embodiments, an electrochemical modifier is incorporatedduring the above described polymerization process. For example, in someembodiments, an electrochemical modifier in the form of metal particles,metal paste, metal salt, metal oxide or molten metal can be dissolved orsuspended into the mixture from which the gel resin is produced

Exemplary electrochemical modifiers for producing composite materialsmay fall into one or more than one of the chemical classifications. Insome embodiments, the electrochemical modifier is a saccharide,including but not limited to, chitin, chitosan, glucose, sucrose,fructose, cellulose, and combinations thereof. In one embodiment, theelectrochemical modifier is a biopolymer such as lignin. In oneembodiment, the electrochemical modifier is a protein such as gelatin.In one embodiment, the electrochemical modifier is a biopolymer such aslignin. In one embodiment, the electrochemical modifier is an aminecompound such as urea or melamine, or combinations thereof. In certainembodiments, the electrochemical modifier is a halogen salt, includingbut not limited to sodium chloride, lithium bromide, potassium fluoride,and combinations thereof. In certain embodiments, the electrochemicalmodifier is a nitrate salt, including but not limited to lithiumnitrate, sodium nitrate, and combinations thereof. In certainembodiments, the electrochemical modifier is a carbide compound,including but not limited to calcium carbide, silicon carbide, andcombinations thereof. In certain embodiments, the electrochemicalmodifier comprises a metal, and exemplary species includes, but are notlimited to aluminum isoproproxide, manganese acetate, nickel acetate,iron acetate, tin chloride, silicon chloride, and combinations thereof.In certain embodiments, the electrochemical modifier is a phosphatecompound, including but not limited to phytic acid, phosphoric acid,ammonium dihydrogenphosphate, and combinations thereof. In certainembodiments, the electrochemical modifier comprises silicon, andexemplary species includes, but are not limited to silicon powders,silicon nanotubes, polycrystalline silicon, nanocrystalline silicon,amorphous silicon, porous silicon, nano sized silicon, nano-featuredsilicon, nano-sized and nano-featured silicon, silicyne, and blacksilicon, and combinations thereof.

Electrochemical modifiers can combined with a variety of polymer systemsthrough either physical mixing or chemical reactions with latent (orsecondary) polymer functionality. Examples of latent polymerfunctionality include, but are not limited to, epoxide groups,unsaturation (double and triple bonds), acid groups, alcohol groups,amine groups, basic groups. Crosslinking with latent functionality canoccur via heteroatoms (e.g. vulcanization with sulfur, acid/base/ringopening reactions with phosphoric acid), reactions with organic acids orbases (described above), coordination to transition metals (includingbut not limited to Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ag, Au),ring opening or ring closing reactions (rotaxanes, spiro compounds,etc.).

Polymerization to form a polymer gel can be accomplished by variousmeans described in the art and may include addition of anelectrochemical modifier. For instance, polymerization can beaccomplished by incubating suitable polymer precursor materials, andoptionally an electrochemical modifier, in the presence of a suitablecatalyst for a sufficient period of time. The time for polymerizationcan be a period ranging from minutes or hours to days, depending on thetemperature (the higher the temperature the faster, the reaction rate,and correspondingly, the shorter the time required). The polymerizationtemperature can range from room temperature to a temperature approaching(but lower than) the boiling point of the starting solution. Forexample, in some embodiments the polymer gel is aged at temperaturesfrom about 20° C. to about 120° C., for example about 20° C. to about100° C. Other embodiments include temperature ranging from about 30° C.to about 90° C., for example about 45° C. or about 85° C. In otherembodiments, the temperature ranges from about 65° C. to about 80° C.,while other embodiments include aging at two or more temperatures, forexample about 45° C. and about 75-85° C. or about 80-85° C.

Electrochemical modifiers can also be added to the polymer systemthrough physical blending. Physical blending can include but is notlimited to melt blending of polymers and/or co-polymers, the inclusionof discrete particles, chemical vapor deposition of the electrochemicalmodifier and coprecipitation of the electrochemical modifier and themain polymer material.

In another embodiment the electrochemical modifier is a particle. Theparticles of electrochemical modifier can be added with differingparticle size distributions. In one embodiment the electrochemicalmodifier particles have a D50 of 10 nm or 50 nm or 100 nm or 150 nm or200 nm or 500 nm or 1 um or 1.5 um or 2 um or 3 um or 5 um or 10 um or20 um or 40 um or up to 50 um, or up to 100 um. In some embodiments thepolymer and particle form a mixture. In other embodiments the particleis covalently bonded to the polymer. In other embodiments the particleis ironically bonded to the polymer. In some cases the particle issilicon, in other cases the particles are a different Group 14 elements(Ge, Sn, Pb), Group 15 elements (P, As, Sb), Group 16 elements (S, Se,Te). In some cases the particle comprises a single element, in othercases it comprises a mixture of two or more elements.

Electrochemical modifier particles can be dispersed in the organicpolymer solution or pre-polymer in a variety of ways. In one embodiment,the particles are dispersed by sonication. In another embodiment, theparticles are dispersed by mixing. In another embodiment, the particlesare dispersed by modifying the surface chemistry of the particles or thepH of the solution. In another embodiment, the particles are dispersedby use of a surfactant. In one embodiment, the surfactant is SPAN 80. Inanother embodiment the particles are dispersed in an emulsion orsuspension. In one embodiment the surfactant is used in combination witha hydrocarbon solvent. In one embodiment, the hydrocarbon iscyclohexane. In one embodiment the hydrocarbon is mineral oil. Inanother embodiment the hydrocarbon is vegetable oil.

In some instances the electrochemical modifier can be added via a metalsalt solution. The metal salt solution or suspension may comprise acidsand/or alcohols to improve solubility of the metal salt. In yet anothervariation, the polymer gel (either before or after an optional dryingstep) is contacted with a paste comprising the electrochemical modifier.In yet another variation, the polymer gel (either before or after anoptional drying step) is contacted with a metal or metal oxide solcomprising the desired electrochemical modifier.

In addition to the above exemplified electrochemical modifiers, thecomposite materials may comprise one or more additional forms (i.e.,allotropes) of carbon. In this regard, it has been found that inclusionof different allotropes of carbon such as graphite, amorphous carbon,diamond, C60, carbon nanotubes (e.g., single and/or multi-walled),graphene and/or carbon fibers into the composite materials is effectiveto optimize the electrochemical properties of the composite materials.The various allotropes of carbon can be incorporated into the carbonmaterials during any stage of the preparation process described herein.For example, during the solution phase, during the gelation phase,during the curing phase, during the pyrolysis phase, during the millingphase, or after milling. In some embodiments, the second carbon form isincorporated into the composite material by adding the second carbonform before or during polymerization of the polymer gel as described inmore detail herein. The polymerized polymer gel containing the secondcarbon form is then processed according to the general techniquesdescribed herein to obtain a carbon material containing a secondallotrope of carbon.

In some embodiments the organic polymer and the electrochemical modifierhave different solvents, ratios of solvents, mixtures of solvents,catalysts type, catalyst ratios, solvent pH, type of acid, or base.

It is expected that by changing either the relative solids concentrationof the carbon containing polymer solution and/or the relative solidsconcentration of the electrochemical modifier containing polymersolution, the electrochemical modifier content of the final compositecan be varied. In one embodiment the solids concentration of the organicpolymer solution can be varied between 1% to 99% solids or from 10% to90% solids, or from 20% to 80% solids or from 20% to 50% or from 30% to40% solids. In one embodiment the solids concentration of the polymersolution is 35%. In one embodiment the solids concentration of theelectrochemical modifier polymer solution can be varied between 1% to99% solids or from 10% to 90% solids, or from 20% to 80% solids or from20% to 50% or from 30% to 40% solids. In one embodiment the solidsconcentration of the electrochemical modifier solution is 35%. In oneembodiment the electrochemical modifier is a TEOS polymer is mixed withethanol. In other embodiments, the TEOS polymer is mixed with acetone,or isopropyl alcohol.

Changing the ratio of organic polymer to the electrochemical modifierpolymer solutions in any given mixture is expected to alter the finalratio of the carbon to electrochemical modifier in the final composite.In one embodiment the ratio of organic polymer to electrochemicalmodifier polymer is about 10:1 or 9:1 or 8:1 or 7:1 or 6:1 or 5:1 or 4:1or 3:1 or 2:1, or 1:1, or 1:2, or 1:3 or 1:4 or 1:5, or 1:6 or 1:7 or1:8 or 1:9 or 1:10.

In one embodiment the organic polymer/electrochemical modifier polymersolution is heated until a gel is formed. In one embodiment a TEOS/RFsolution is heated until a gel is formed. In one embodiment the heatingis carried out in a sealed container. In one embodiment the heating iscarried out in a polymer reactor. For example, a stirred polymerreactor. In one embodiment the solution is heated in an emulsion, or inan inverse emulsion or in a suspension. The temperature at whichgelation takes place is known to impact the structure of the polymer andcan be modified to control the structure of the final compositematerial. In one embodiment the gel is formed at 40° C. or 50° C. or 60°C. or 70° C. or 80° C. or 90° C. or 100° C. or 110° C. or 120° C. or130° C. In one embodiment the gel is formed in a two-step reaction. Forexample one temperature to cause the organic polymer to gel and adifferent temperature to cause the electrochemical modifier polymer togel. In one embodiment the two step polymerization is carried out at 40°C. or 50° C. or 60° C. or 70° C. or 80° C. or 90° C. or 100° C. or 110°C. or 120° C. or 130° C. and then the second step is carried out at 40°C. or 50° C. or 60° C. or 70° C. or 80° C. or 90° C. or 100° C. or 110°C. or 120° C. or 130° C. In some embodiments the organic polymer isfully gelled and then an electrochemical modifier polymer solution isadded through a solvent exchange to dope the organic polymer. In someembodiments the electrochemical modifier polymer is fully gelled andthen an organic polymer solution is added through a solvent exchange todope the electrochemical modifier polymer.

In some embodiments, the fraction of solvent in the reaction mixture islow or the reaction can be essentially solvent free. For example, thefraction of solvent in the reaction mixture can be can less than 80% ofthe total mass of reaction mixture, for example less than 70%, forexample less than 60%, for example less than 50%, for example less than40%, for example less than 30%, for example less than 20%, for exampleless than 10%, for example less than 5%, for example less than 1%, forexample less than 0.1%, for example less than 0.01%. Without being boundby theory, a pyrolyzed carbon yield from a polymeric material can beabout 50%. Accordingly, the ratio of pyrolyzed carbon produced per unitmass of polymer processed can be less than about 10, less than about 7,less than about 5, less than about 4, less than about 3, less than about2.5, less than about 2.1. In some embodiments, the ratio of pyrolyzedcarbon produced per unit mass of polymer processed is about 2. In someembodiments, the ratio of pyrolyzed carbon produced per unit mass ofpolymer processed is less than 2.

The pyrolyzed carbon produced from low solvent or essentiallysolvent-free reaction mixtures can be activated, and the ratio ofactivated carbon to polymer processed is higher than the ratio ofpyrolyzed carbon to polymer processed, depending on the level ofactivation desired. Without being bound by theory, a activated carbonyield from a pyrolyzed carbon material can be about 50%. Accordingly,the ratio of activated carbon produced per unit mass of polymerprocessed can be less than about 14, less than about 10, less than about8, less than about 6, less than about 5, less than about 4.5, less thanabout 4.1. In some embodiments, the ratio of activated carbon producedper unit mass of polymer processed is about 4 or lower.

The structure of the polymer precursors suitable for use in a lowsolvent or essentially solvent free reaction mixture is not particularlylimited, provided that the polymer precursor is capable of reacting withanother polymer precursor or with a second polymer precursor to form apolymer. Polymer precursors include amine-containing compounds,alcohol-containing compounds and carbonyl-containing compounds, forexample in some embodiments the polymer precursors are selected from analcohol, a phenol, a polyalcohol, a sugar, an alkyl amine, an aromaticamine, an aldehyde, a ketone, a carboxylic acid, an ester, a urea, anacid halide and an isocyanate.

In one embodiment employing a low or essentially solvent free reactionmixture, the method comprises use of a first and second polymerprecursor, and in some embodiments the first or second polymer precursoris a carbonyl containing compound and the other of the first or secondpolymer precursor is an alcohol containing compound. In someembodiments, a first polymer precursor is a phenolic compound and asecond polymer precursor is an aldehyde compound (e.g., formaldehyde).In one embodiment, of the method the phenolic compound is phenol,resorcinol, catechol, hydroquinone, phloroglucinol, or a combinationthereof; and the aldehyde compound is formaldehyde, acetaldehyde,propionaldehyde, butyraldehyde, benzaldehyde, cinnamaldehyde, or acombination thereof. In a further embodiment, the phenolic compound isresorcinol, phenol or a combination thereof, and the aldehyde compoundis formaldehyde. In yet further embodiments, the phenolic compound isresorcinol and the aldehyde compound is formaldehyde. In someembodiments, the polymer precursors are alcohols and carbonyl compounds(e.g., resorcinol and aldehyde) and they are present in a ratio of about0.5:1.0, respectively.

The polymer precursor materials suitable for low or essentially solventfree reaction mixture as disclosed herein include (a) alcohols, phenoliccompounds, and other mono- or polyhydroxy compounds and (b) aldehydes,ketones, and combinations thereof. Representative alcohols in thiscontext include straight chain and branched, saturated and unsaturatedalcohols. Suitable phenolic compounds include polyhydroxy benzene, suchas a dihydroxy or trihydroxy benzene. Representative polyhydroxybenzenes include resorcinol (i.e., 1,3-dihydroxy benzene), catechol,hydroquinone, and phloroglucinol. Other suitable compounds in thisregard are bisphenols, for instance, bisphenol A. Mixtures of two ormore polyhydroxy benzenes can also be used. Phenol (monohydroxy benzene)can also be used. Representative polyhydroxy compounds include sugars,such as glucose, sucrose, fructose, chitin and other polyols, such asmannitol. Aldehydes in this context include: straight chain saturatedaldehydes such as methanal (formaldehyde), ethanal (acetaldehyde),propanal (propionaldehyde), butanal (butyraldehyde), and the like;straight chain unsaturated aldehydes such as ethenone and other ketenes,2-propenal (acrylaldehyde), 2-butenal (crotonaldehyde), 3 butenal, andthe like; branched saturated and unsaturated aldehydes; andaromatic-type aldehydes such as benzaldehyde, salicylaldehyde,hydrocinnamaldehyde, and the like. Suitable ketones include: straightchain saturated ketones such as propanone and 2 butanone, and the like;straight chain unsaturated ketones such as propenone, 2 butenone, and 3butenone (methyl vinyl ketone) and the like; branched saturated andunsaturated ketones; and aromatic-type ketones such as methyl benzylketone (phenylacetone), ethyl benzyl ketone, and the like. The polymerprecursor materials can also be combinations of the precursors describedabove.

In some embodiments, one polymer precursor in the low or essentiallysolvent free reaction mixture is an alcohol-containing species andanother polymer precursor is a carbonyl-containing species. The relativeamounts of alcohol-containing species (e.g., alcohols, phenoliccompounds and mono- or poly-hydroxy compounds or combinations thereof)reacted with the carbonyl containing species (e.g. aldehydes, ketones orcombinations thereof) can vary substantially. In some embodiments, theratio of alcohol-containing species to aldehyde species is selected sothat the total moles of reactive alcohol groups in thealcohol-containing species is approximately the same as the total molesof reactive carbonyl groups in the aldehyde species. Similarly, theratio of alcohol-containing species to ketone species may be selected sothat the total moles of reactive alcohol groups in the alcoholcontaining species is approximately the same as the total moles ofreactive carbonyl groups in the ketone species. The same general 1:1molar ratio holds true when the carbonyl-containing species comprises acombination of an aldehyde species and a ketone species.

In other embodiments, the polymer precursor in the low or essentiallysolvent free reaction mixture is a urea or an amine containing compound.For example, in some embodiments the polymer precursor is urea,melamine, hexamethylenetetramine (HMT) or combination thereof. Otherembodiments include polymer precursors selected from isocyanates orother activated carbonyl compounds such as acid halides and the like.

Some embodiments of the disclosed methods include preparation of low orsolvent-free polymer gels (and carbon materials) comprisingelectrochemical modifiers. Such electrochemical modifiers include, butare not limited to nitrogen, silicon, and sulfur. In other embodiments,the electrochemical modifier comprises fluorine, iron, tin, silicon,nickel, aluminum, zinc, or manganese. The electrochemical modifier canbe included in the preparation procedure at any step. For example, insome the electrochemical modifier is admixed with the mixture, thepolymer phase or the continuous phase.

The blending of one or more polymer precursor components in the absenceof solvent can be accomplished by methods described in the art, forexample ball milling, jet milling, Fritsch milling, planetary mixing,and other mixing methodologies for mixing or blending solid particleswhile controlling the process conditions (e.g., temperature). The mixingor blending process can be accomplished before, during, and/or after (orcombinations thereof) incubation at the reaction temperature.

Reaction parameters include aging the blended mixture at a temperatureand for a time sufficient for the one or more polymer precursors toreact with each other and form a polymer. In this respect, suitableaging temperature ranges from about room temperature to temperatures ator near the melting point of one or more of the polymer precursors. Insome embodiments, suitable aging temperature ranges from about roomtemperature to temperatures at or near the glass transition temperatureof one or more of the polymer precursors. For example, in someembodiments the solvent free mixture is aged at temperatures from about20° C. to about 600° C., for example about 20° C. to about 500° C., forexample about 20° C. to about 400° C., for example about 20° C. to about300° C., for example about 20° C. to about 200° C. In certainembodiments, the solvent free mixture is aged at temperatures from about50 to about 250° C.

The porous carbon material can be achieved via pyrolysis of a polymerproduced from precursors materials as described above. The temperatureand dwell time of pyrolysis can be varied, for example the dwell timevan vary from 1 min to 10 min, from 10 min to 30 min, from 30 min to 1hour, for 1 hour to 2 hours, from 2 hours to 4 hours, from 4 hours to 24h. The temperature can be varied, for example, the pyrolysis temperaturecan vary from 200 to 300° C., from 250 to 350° C., from 350° C. to 450°C., from 450° C. to 550° C., from 540° C. to 650° C., from 650° C. to750° C., from 750° C. to 850° C., from 850° C. to 950° C., from 950° C.to 1050° C., from 1050° C. to 1150° C., from 1150° C. to 1250° C. Thepyrolysis can be accomplished in an inert gas, for example nitrogen, orargon. In some embodiments, an alternate gas is used, or mixture of aninert gas such as nitrogen with the alternate gas. Suitable alternategases in this context include, but are not limited to, carbon dioxide,carbon monoxide, water (steam), air, oxygen, and further combinationsthereof.

Either prior to the pyrolysis, and/or after pyrolysis, the porous carbonparticle may be subjected to a particle size reduction. The particlesize reduction can be accomplished by a variety of techniques known inthe art, for example by jet milling in the presence of various gasesincluding air, nitrogen, argon, helium, supercritical steam, and othergases known in the art. Other particle size reduction methods, such asgrinding, ball milling, jet milling, water jet milling, and otherapproaches known in the art are also envisioned.

In some embodiments, the surface area of the porous carbon material cancomprise a surface area greater than 500 m²/g, for example greater than750 m²/g, for example greater than 1000 m²/g, for example greater than1250 m²/g, for example greater than 1500 m²/g, for example greater than1750 m²/g, for example greater than 2000 m²/g, for example greater than2500 m²/g, for example greater than 3000 m²/g. In other embodiments, thesurface area of the porous carbon material can be less than 500 m²/g. Insome embodiments, the surface area of the porous carbon material isbetween 200 and 500 m²/g. In some embodiments, the surface area of theporous carbon material is between 100 and 200 m²/g. In some embodiments,the surface area of the porous carbon material is between 50 and 100m²/g. In some embodiments, the surface area of the porous carbonmaterial is between 10 and 50 m²/g. In some embodiments, the surfacearea of the porous carbon material can be less than 10 m²/g.

The pore volume of the porous carbon material is greater than 0.5 cm³/g,for example greater than 0.6 cm³/g, for example greater than 0.7 cm³/g,for example greater than 0.8 cm³/g, for example greater than 0.9 cm³/g,for example greater than 1.0 cm³/g, for example greater than 1.1 cm³/g,for example greater than 1.2 cm³/g, for example greater than 1.4 cm³/g,for example greater than 1.6 cm³/g, for example greater than 1.8 cm³/g,for example greater than 2.0 cm³/g. In other embodiments, the porevolume of the porous silicon material is less than 0.5 cm³, for examplebetween 0.1 cm³/g and 0.5 cm³/g. In certain other embodiments, the porevolume of the porous silicon material is between 0.01 cm³/g and 0.1cm³/g.

In some other embodiments, the porous carbon material comprises a tapdensity of less than 1.0 g/cm³, for example less than 0.8 g/cm³, forexample less than 0.6 g/cm³, for example less than 0.5 g/cm³, forexample less than 0.4 g/cm³, for example less than 0.3 g/cm³, forexample less than 0.2 g/cm³, for example less than 0.1 g/cm³.

The surface functionality of the porous carbon material can vary. Oneproperty which can be predictive of surface functionality is the pH ofthe porous carbon material. The presently disclosed porous carbonmaterials comprise pH values ranging from less than 1 to about 14, forexample less than 5, from 5 to 8 or greater than 8. In some embodiments,the pH of the porous carbon is less than 4, less than 3, less than 2 oreven less than 1. In other embodiments, the pH of the porous carbon isbetween about 5 and 6, between about 6 and 7, between about 7 and 8 orbetween 8 and 9 or between 9 and 10. In still other embodiments, the pHis high and the pH of the porous carbon ranges is greater than 8,greater than 9, greater than 10, greater than 11, greater than 12, oreven greater than 13.

The pore volume distribution of the porous carbon scaffold can vary. Forexample, the % micropores can comprise less than 30%, for example lessthan 20%, for example less than 10%, for example less than 5%, forexample less than 4%, for example less than 3%, for example less than2%, for example less than 1%, for example less than 0.5%, for exampleless than 0.2%, for example, less than 0.1%. In certain embodiments,there is no detectable micropore volume in the porous carbon scaffold.

The mesopores comprising the porous carbon scaffold material can vary.For example, the % mesopores can comprise less than 30%, for exampleless than 20%, for example less than 10%, for example less than 5%, forexample less than 4%, for example less than 3%, for example less than2%, for example less than 1%, for example less than 0.5%, for exampleless than 0.2%, for example, less than 0.1%. In certain embodiments,there is no detectable mesopore volume in the porous carbon scaffold.

In some embodiments, the pore volume distribution of the porous carbonscaffold material comprises more than 50% macropores, for example morethan 60% macropores, for example more than 70% macropores, for examplemore than 80% macropores, for example more than 90% macropores, forexample more than 95% macropores, for example more than 98% macropores,for example more than 99% macropores, for example more than 99.5%macropores, for example more than 99.9% macropores.

In certain preferred embodiments, the pore volume of the porous carbonscaffold comprises a blend of micropores, mesopores, and macropores.Accordingly, in certain embodiments, the porous carbon scaffoldcomprises 0-20% micropores, 30-70% mesopores, and less than 10%macropores. In certain other embodiments, the porous carbon scaffoldcomprises 0-20% micropores, 0-20% mesopores, and 70-95% macropores. Incertain other embodiments, the porous carbon scaffold comprises 20-50%micropores, 50-80% mesopores, and 0-10% macropores. In certain otherembodiments, the porous carbon scaffold comprises 40-60% micropores,40-60% mesopores, and 0-10% macropores. In certain other embodiments,the porous carbon scaffold comprises 80-95% micropores, 0-10% mesopores,and 0-10% macropores. In certain other embodiments, the porous carbonscaffold comprises 0-10% micropores, 30-50% mesopores, and 50-70%macropores. In certain other embodiments, the porous carbon scaffoldcomprises 0-10% micropores, 70-80% mesopores, and 0-20% macropores. Incertain other embodiments, the porous carbon scaffold comprises 0-20%micropores, 70-95% mesopores, and 0-10% macropores. In certain otherembodiments, the porous carbon scaffold comprises 0-10% micropores,70-95% mesopores, and 0-20% macropores.

In certain embodiments, the % of pore volume in the porous carbonscaffold representing pores between 100 and 1000 A (10 and 100 nm)comprises greater than 30% of the total pore volume, for example greaterthan 40% of the total pore volume, for example greater than 50% of thetotal pore volume, for example greater than 60% of the total porevolume, for example greater than 70% of the total pore volume, forexample greater than 80% of the total pore volume, for example greaterthan 90% of the total pore volume, for example greater than 95% of thetotal pore volume, for example greater than 98% of the total porevolume, for example greater than 99% of the total pore volume, forexample greater than 99.5% of the total pore volume, for example greaterthan 99.9% of the total pore volume.

In certain preferred embodiments, the pore volume in the porous carbonscaffold representing pores between 100 and 1000 A (10 and 100 nm) isgreater than 0.1 cm³/g, for example greater than 0.2 cm³/g, for examplegreater than 0.3 cm³/g, for example greater than 0.4 cm³/g, for examplegreater than 0.5 cm³/g, for example greater than 0.6 cm³/g, for examplegreater than 0.7 cm³/g, for example greater than 0.8 cm³/g, for examplegreater than 0.9 cm³/g, for example greater than 1.0 cm³/g, for examplegreater than 1.1 cm³/g, for example greater than 1.2 cm³/g, for examplegreater than 1.3 cm³/g, for example greater than 1.4 cm³/g, for examplegreater than 1.5 cm³/g, for example greater than 2.0 cm³/g.

In certain preferred embodiments, the porous carbon scaffold comprises atotal pore volume greater than 0.5 cm³/g and the % macropores is greaterthan 80%. In certain other preferred embodiments, the porous carbonscaffold comprises a total pore volume is greater than 1.0 cm³/g and the% macropores is greater than 90%. In certain preferred embodiments, theporous carbon scaffold comprises a total pore volume greater than 0.5cm³/g and the % pore between 100 and 1000 A is greater than 80%. Incertain other preferred embodiments, the porous carbon scaffoldcomprises a total pore volume is greater than 1.0 cm³/g and the % porebetween 100 and 1000 A is greater than 90%.

The porous carbon scaffold, i.e., the carbon without electrochemicalmodifier, may comprise a majority (e.g., >50%) of the total pore volumeresiding in pores of certain diameter. For example, in some embodimentsgreater than 50%, greater than 60%, greater than 70%, greater than 80%,greater than 90% or even greater than 95% of the total pore volumeresides in pores having a diameter of 1 nm or less. In other embodimentsgreater than 50%, greater than 60%, greater than 70%, greater than 80%,greater than 90% or even greater than 95% of the total pore volumeresides in pores having a diameter of 100 nm or less. In otherembodiments greater than 50%, greater than 60%, greater than 70%,greater than 80%, greater than 90% or even greater than 95% of the totalpore volume resides in pores having a diameter of 0.5 nm or less.

In some embodiments, the tap density of the carbon withoutelectrochemical modifier may be predictive of their ability toincorporate electrochemical modifiers and hence electrochemicalperformance, for example the volumetric capacity. While not limiting inany way, the pore volume of a carbon without electrochemical modifiermaterial may be related to its tap density and carbon withoutelectrochemical modifiers having low pore volume are sometimes found tohave high tap density (and vice versa). Accordingly, carbon withoutelectrochemical modifier having low tap density (e.g., <0.3 g/cc),medium tap density (e.g., from 0.3 to 0.5 g/cc) or high tap density(e.g., >0.5 g/cc) are provided.

In yet some other embodiments, the carbon without electrochemicalmodifier comprises a tap density greater than or equal to 0.3 g/cc. Inyet some other embodiments, the carbon without electrochemical modifiercomprise a tap density ranging from about 0.3 g/cc to about 0.5 g/cc. Insome embodiments, the carbon without electrochemical modifier comprise atap density ranging from about 0.35 g/cc to about 0.45 g/cc. In someother embodiments, the carbon without electrochemical modifier comprisea tap density ranging from about 0.30 g/cc to about 0.40 g/cc. In someembodiments, the carbon without electrochemical modifier comprise a tapdensity ranging from about 0.40 g/cc to about 0.50 g/cc. In someembodiments of the foregoing, the carbon without electrochemicalmodifier comprises a medium total pore volume (e.g., from about 0.1 cc/gto about 0.6 cc/g).

In yet some other embodiments, the carbon without electrochemicalmodifier can comprise a tap density greater than about 0.5 g/cc. In someother embodiments, the carbon without electrochemical modifier comprisesa tap density ranging from about 0.5 g/cc to about 2.0 g/cc. In someother embodiments, the carbon without electrochemical modifier comprisea tap density ranging from about 0.5 g/cc to about 1.0 g/cc. In someembodiments, the carbon without electrochemical modifier comprise a tapdensity ranging from about 0.5 g/cc to about 0.75 g/cc. In someembodiments, the carbon without electrochemical modifier comprise a tapdensity ranging from about 0.75 g/cc to about 1.0 g/cc, for example fromabout 0.75 g/cc to about 0.95 g/cc, for example, from about 0.75 toabout 1.2 g/cc. In some embodiments of the foregoing, the carbon withoutelectrochemical modifier comprises a low, medium or high total porevolume. Their skeletal density as measured by helium pycnometry can alsocharacterize the density of the carbon without electrochemical modifier.In certain embodiments, the skeletal density of the carbon withoutelectrochemical modifier ranges from about 1 g/cc to about 3 g/cc, forexample from about 1.5 g/cc to about 2.3 g/cc. In other embodiments, theskeletal density ranges from about 1.5 cc/g to about 1.6 cc/g, fromabout 1.6 cc/g to about 1.7 cc/g, from about 1.7 cc/g to about 1.8 cc/g,from about 1.8 cc/g to about 1.9 cc/g, from about 1.9 cc/g to about 2.0cc/g, from about 2.0 cc/g to about 2.1 cc/g, from about 2.1 cc/g toabout 2.2 cc/g or from about 2.2 cc/g to about 2.3 cc/g, from about 2.3cc to about 2.4 cc/g, for example from about 2.4 cc/g to about 2.5 cc/g.

In all cases the properties of the carbon without electrochemicalmodifier can easily be measured before incorporation of theelectrochemical modifier. The properties of the carbon withoutelectrochemical modifier can also be measured by removal of theelectrochemical modifier after the fact. In the case of silicon this caneasily be accomplished by dissolving the silicon with a solvent thatdoes not impact the carbon and then measuring the properties of thecarbon without electrochemical modifier.

C. Introduction of Silicon into Scaffold Materials to Create CompositeMaterials

Nano-sized silicon is difficult to handle and to process in traditionalelectrodes. Due to the high surface area and preference to agglomerate,uniform dispersion and coating requires special procedures and/or bindersystems. To truly be a drop in replacement for existing graphite anodematerials, the next generation Si—C material needs to be micron-sized.In a preferred embodiment, the size distribution for the composite isrelatively uniform, with upper and lower bounds within a preferredrange, for example, Dv10 of no less than 5 nm, a Dv50 between 500 nm and5 um, and a Dv90 no greater than 50 um. In certain embodiments, thecomposite particles are comprised of the following size distribution:Dv10 of no less than 50 nm, a Dv50 between 1 um and 10 um, and a Dv90 nogreater than 30 um. In certain other embodiments, the compositeparticles are comprised of the following size distribution: Dv10 of noless than 100 nm, a Dv50 between 2 um and 8 um, and a Dv90 no greaterthan 20 um. In certain further embodiments, the composite particles arecomprised of the following size distribution: Dv10 of no less than 250nm, a Dv50 between 4 um and 6 um, and a Dv90 no greater than 15 um.

Unlike existing composite materials which bury silicon into a mass ofinactive material, we understand that to achieve optimal performance,silicon needs room to expand and contract. Our high pore volume carbonsare seen as the inspiration in which to embed or deposit silicon, and doso in a engineered fashion, filling pore volume of desired range tocreate impregnated carbon material of the desired size range. Thus thetemplate, for example the porous carbon material, plays an importantrole as a framework and in-situ template for expansion and contractionas well as contributing to the overall electron and ion conductioncapability of the composite particle. This scaffold structure will allowfor the movement of electrons and possible ions, but its primary role isto simply affix the silicon to a single location, allowing it tooutwardly expand and contract while remaining lodged inside pores.

In certain embodiments, the silicon is introduced into the porous carbonby nanoparticle impregnation. Accordingly, a nano-sized or nano-sizedand nano-featured silicon is first produced. In a preferred embodiment,the nano sized or nano-sized and nano-featured silicon is producedaccording to methods described in U.S. No. 62/205,542 “Nano-FeaturedPorous Silicon Materials,” U.S. No. 62/208,357 “Nano-Featured PorousSilicon Materials,” and/or U.S. No. 62/209,651 “Composites of PorousNano-Featured Silicon Materials and Carbon Materials,” the fulldisclosures of which are hereby incorporated by reference in theirentireties for all purposes.

The porous carbon can be mixed with the nano silicon, for example in astirred reactor vessel wherein the carbon particles, for example microsized porous carbon particles, are co-suspended with nano silicon of thedesired particle size. The suspension milieu can be varied as known inthe art, for example can be aqueous or non-aqueous. In certainembodiments, the suspension fluid can be multi-component, comprisingeither miscible or non-miscible co-solvents. Suitable co-solvents foraqueous (water) milieu include, but are not limited to, acetone,ethanol, methanol, and others known in the art. A wide variety ofnon-water soluble milieu are also known in the art, including, but notlimited to, heptane, hexane, cyclohexane, oils, such as mineral oils,vegetable oils, and the like. Without being bound by theory, mixingwithin the reactor vessel allows for diffusion of the siliconnanoparticles within the porous carbon particle. The resulting nanosilicon impregnated carbon particles can then be harvested, for example,by centrifugation, filtration, and subsequent drying, all as known inthe art.

To this end, the porous carbon particles with the desired extent andtype of porosity are subject to processing that results in creation ofsilicon within said porosity. For this processing, the porous carbonparticles can be first particle size reduced, for example to provide aDv,50 between 1 and 1000 microns, for example between 1 and 100 microns,for example between 1 and 50 microns, for example between 1 and 20microns, for example between 1 and 15 microns, for example between 2 and12 microns, for example between 5 and 10 microns. The particle sizereduction can be carried out as known in the art, and as describedelsewhere herein, for instance by jet milling.

In a preferred embodiment, silicon is created within the pores of theporous carbon by subjecting the porous carbon particles to silane gas atelevated temperature and the presence of a silicon-containing gas,preferably silane, in order to achieve silicon deposition via chemicalvapor deposition (CVD). The silane gas can be mixed with other inertgases, for example, nitrogen gas. The temperature and time of processingcan be varied, for example the temperature can be between 300 and 400°C., for example between 400 and 500° C., for example between 500 and600° C., for example between 600 and 700° C., for example between 700and 800° C., for example between 800 and 900° C. The mixture of gas cancomprise between 0.1 and 1% silane and remainder inert gas.Alternatively, the mixture of gas can comprise between 1% and 10% silaneand remainder inert gas. Alternatively, the mixture of gas can comprisebetween 10% and 20% silane and remainder inert gas. Alternatively, themixture of gas can comprise between 20% and 50% silane and remainderinert gas. Alternatively, the mixture of gas can comprise above 50%silane and remainder inert gas. Alternatively, the gas can essentiallybe 100% silane gas. The reactor in which the CVD process is carried outis according to various designs as known in the art, for example in afluid bed reactor, a static bed reactor, an elevator kiln, a rotarykiln, a box kiln, or other suitable reactor type. The reactor materialsare suitable for this task, as known in the art. In a preferredembodiment, the porous carbon particles are process under condition thatprovide uniform access to the gas phase, for example a reactor whereinthe porous carbon particles are fluidized, or otherwise agitated toprovide said uniform gas access.

In some embodiments, the CVD process is a plasma-enhanced chemical vapordeposition (PECVD) process. This process is known in the art to provideutility for depositing thin films from a gas state (vapor) to a solidstate on a substrate. Chemical reactions are involved in the process,which occur after creation of a plasma of the reacting gases. The plasmais generally created by RF (AC) frequency or DC discharge between twoelectrodes, the space between which is filled with the reacting gases.In certain embodiments, the PECVD process is utilized for porous carbonthat is coated on a substrate suitable for the purpose, for example acopper foil substrate. The PECVD can be carried out at varioustemperatures, for example between 300 and 800° C., for example between300 and 600° C., for example between 300 and 500° C., for examplebetween 300 and 400° C., for example at 350° C. The power can be varied,for example 25W RF, and the silane gas flow required for processing carbe varied, and the processing time can be varied as known in the art.

The silicon that is impregnated into the porous carbon, regardless ofthe process, is envisioned to have certain properties that are optimalfor utility as an energy storage material. For example, the size andshape of the silicon can be varied accordingly to match, while not beingbound by theory, the extent and nature of the pore volume within theporous carbon particle. For example, the silicon can be impregnated,deposited by CVD, or other appropriate process into pores within theporous carbon particle comprising pore sizes between 5 nm and 1000 nm,for example between 10 nm and 500 nm, for example between 10 nm and 200nm, for example between 10 nm and 100 nm, for example between 33 nm and150 nm, for example between 20 nm and 100 nm. Other ranges of carbonpores sizes with regards to fractional pore volume, whether micropores,mesopores, or macropores, are also envisioned as described elsewherewithin this disclosure. The oxygen content in silicon can be less than50%, for example, less than 30%, for example less than 20%, for exampleless than 15%, for example, less than 10%, for example, less than 5%,for example, less than 1%, for example less than 0.1%. In certainembodiments, the oxygen content in the silicon is between 1 and 30%. Incertain embodiments, the oxygen content in the silicon is between 1 and20%. In certain embodiments, the oxygen content in the silicon isbetween 1 and 10%. In certain embodiments, the oxygen content in theporous silicon materials is between 5 and 10%.

In certain embodiments wherein the silicon contains oxygen, the oxygenis incorporated such that the silicon exists as a mixture of silicon andsilicon oxides of the general formula SiOx, where X is a non-integer(real number) can vary continuously from 0.01 to 2. In certainembodiments, the fraction of oxygen present on the surface of thenano-feature porous silicon is higher compared to the interior of theparticle.

In certain embodiments, the silicon comprises crystalline silicon. Incertain embodiments, the silicon comprises polycrystalline silicon. Incertain embodiments, the silicon comprises micro-polycrystallinesilicon. In certain embodiments, the silicon comprisesnano-polycrystalline silicon. In certain other embodiments, the siliconcomprises amorphous silicon. In certain other embodiments, the siliconcomprises both crystalline and non-crystalline silicon.

In certain embodiments, the carbon scaffold to be impregnated orotherwise embedded with silicon can comprise various carbon allotropesand/or geometries. To this end, the carbon scaffold to be impregnated orotherwise embedded with silicon can comprise graphite, nano graphite,graphene, nano graphene, conductive carbon such as carbon black, carbonnanowires, carbon nanotubes, and the like, and combinations thereof.

In certain embodiments, the carbon scaffold that is impregnated orotherwise embedded with silicon is removed to yield the templatedsilicon material with desired size characteristics. The removal of thescaffold carbon can be achieved as known in the art, for example bythermal of chemical activation under conditions wherein the silicon doesnot undergo undesirable changes in its electrochemical properties.Alternatively, if the scaffold is a porous polymer or other materialsoluble in a suitable solvent, the scaffold can be removed bydissolution.

D. Coating of Composite Materials with Carbon

Without being bound by theory, the electrochemical performance of thecomposites produced via silicon impregnation into porous carbonmaterials can be achieved by coating, for example coating the compositematerial in a layer of carbon. In this context, the surface layer cancomprise a carbon layer, as described in the current section, or anothersuitable layer, for example a conductive polymer layer, as described inthe subsequent section.

The surface layer is envisioned to provide for a suitable SEI layer. Inthis context, the surface carbon layer needs to be a good ionicconductor to shuttle Li-ions. Alternatively, the carbon layer cancomprise an artificial SEI layer, for example the carbon layer cancomprise poly(3,4-ethylenedioxythiophene)-co-poly(ethylene glycol)copolymer. The coating may comprise nitrogen and/or oxygen functionalityto further improve the layer with respect to promoting a stable SEIlayer. The coating needs to provide sufficient electrical conductivity,adhesion, and cohesion between particles. The surface should provide astable SEI layer, the latter is typically comprised of species such asLiF, Li₂CO₃, and Li₂O. Inorganic material with relatively low bulkmodulus may provide a more stable SEI layer, for example a moreamorphous vs. crystalline layer is preferred, for instance Li₂CO₃ vs.LiF.

To this end, a layer of carbon can be applied to the silicon-impregnatedcarbon material. Without being bound by theory, this carbon layer shouldprovide low surface area, low surface roughness and/or low degree ofmorphological defects, all in order to provide a more stable SEI layer,higher first cycle efficiency, and greater cycle stability in alithium-ion battery. Various carbon allotropes can be envisioned in thecontext of providing a surface layer to the silicon-impregnated porouscarbon materials, including graphite, graphene, hard of soft carbons,for example pyrolytic carbon.

In alternate embodiments, the aforementioned coating can be achievedwith a precursor solution as known in the art, followed by acarbonization process. For example, particles can be coated by a wursterprocess or related spray drying process known in the art to apply a thinlayer of precursor material on the particles. The precursor coating canthen be pyrolyzed, for example by further fluidization of thewurster-coated particles in the presence of elevated temperature and aninert gas as consistent with descriptions disclosed elsewhere herein.

In alternate embodiments, the particles can be covered in a carbonaceouslayer accomplished by chemical vapor deposition (CVD). Without wishingto be bound by theory, it is believed that CVD methods to deposit carbonlayers (e.g., from a hydrocarbon gas) result in a carbon that isgraphitizable (also referred to as “soft” carbon in the art).Methodologies for CVD generally described in the art can be applied tothe composite materials disclosed herein, for example particles ofporous silicon wherein nano-sized or nano-sized and nano-featuredsilicon has been impregnated or otherwise introduced into the carbonpore volume of the desired range of pore sizes. CVD is generallyaccomplished by subjecting the porous silicon material for a period oftime at elevated temperature in the presence of a suitable depositiongas containing carbon atoms. Suitable gases in this context include, butare not limited to methane, propane, butane, cyclohexane, ethane,propylene, and acetylene. The temperature can be varied, for examplebetween 350 to 1050° C., for example between 350 and 450° C., forexample between 450 and 550° C., for example between 550 and 650° C.,for example between 650 and 750° C., for example between 750 and 850°C., for example between 850 and 950° C., for example between 950 and1050° C. The deposition time can be varied, for example between 0 and 5min, for example between 5 and 15 min, for example between 15 and 30min, for example between 30 and 60 min, for example between 60 and 120min, for example between 120 and 240 min. In some embodiments, thedeposition time is greater than 240 min. In certain embodiments, thedeposition gas is methane and the deposition temperature is greater thanor equal to 950° C. In certain embodiments, the deposition gas ispropane and the deposition temperature is less than or equal to 750° C.In certain embodiments, the deposition gas is cyclohexane and thedeposition temperature is greater than or equal to 800° C.

In certain embodiments, the reactor itself can be agitated, in order toagitate the porous carbon scaffold to be silicon impregnated. Forexample, the impregnation process can be carried out in a static mode,wherein the particles are not agitated, and the silicon-containingreactant flows over, around, or otherwise comes in contact with theparticles to be coated. In other exemplary modes, the particles can befluidized, for example the impregnation with silicon-containing reactantcan be carried out in a fluidized bed reactor. A variety of differentreactor designs can be employed in this context as known in the art,including, but not limited to, elevator kiln, roller hearth kiln, rotarykiln, box kiln, and modified fluidized bed designs.

Accordingly, the present disclosure provides for the manufacturing of acomposite silicon-carbon material, wherein the carbon scaffold materialis a porous carbon material, and wherein the silicon impregnation isachieved by contacting the porous carbon material with asilicon-containing reactant. For example, the process may involve thefollowing steps:

-   -   a) mixing polymer(s) and/or polymer precursor(s) and storing for        a period of time at sufficient temperature to allow for        polymerization of the precursors,    -   b) carbonization of the resulting polymer material to create a        porous carbon material    -   c) subjecting the porous carbon material to elevated temperature        in the presence of a silicon-containing reactant within a static        or agitated reactor, resulting in a silicon-impregnated carbon        material

In another embodiment, the present disclosure provides for themanufacturing of a composite silicon-carbon material, wherein the carbonscaffold material is a porous carbon material, and wherein the siliconimpregnation is achieved by contacting with a silicon-containingreactant, and wherein a terminal carbon coating is achieved bycontacting the composite with a carbon-containing reactant. For example,the process may involve the following steps:

-   -   a) mixing polymer(s) and/or polymer precursor(s) and storing for        a period of time at sufficient temperature to allow for        polymerization of the precursors,    -   b) carbonization of the resulting polymer material to create a        porous carbon material    -   c) subjecting the porous carbon material to elevated temperature        in the presence of a silicon-containing reactant within a static        or agitated reactor, resulting in a silicon-impregnated carbon        material    -   d) subjecting the silicon impregnated carbon material to        elevated temperature in the presence of a carbon-containing        reactant within a static or agitated reactor, resulting in a        terminally carbon coated silicon-carbon composite material.

In another embodiment, the present disclosure provides for themanufacturing of a composite silicon-carbon material, wherein the carbonscaffold material is a porous carbon material, and wherein the siliconimpregnation is achieved by contacting with a silicon-containingreactant, and wherein a terminal conducting polymer coating is achievedby contacting the composite with a conductive polymer, and optionallypyrolyzing the material For example, the process may involve thefollowing steps:

-   -   a) mixing polymer(s) and/or polymer precursor(s) and storing for        a period of time at sufficient temperature to allow for        polymerization of the precursors,    -   b) carbonization of the resulting polymer material to create a        porous carbon material    -   c) subjecting the porous carbon material to elevated temperature        in the presence of a silicon-containing reactant within a static        or agitated reactor, resulting in a silicon-impregnated carbon        material    -   d) subjecting the silicon impregnated carbon material to        elevated temperature in the presence of a conductive polymer        within a static or agitated reactor, resulting in a terminally        conductive polymer coated silicon-carbon composite material    -   e) the materials of (d) can be optionally pyrolyzed.

The silicon-impregnated porous carbon composite material can also beterminally carbon coated via a hydrothermal carbonization wherein theparticles are processed by various modes according to the art.Hydrothermal carbonization can be accomplished in an aqueous environmentat elevated temperature and pressure to obtain a silicon-carboncomposite. Examples of temperature to accomplish the hydrothermalcarbonization vary, for example between 150° C. and 300° C., forexample, between 170° C. and 270° C., for example between 180° C. and260° C., for example, between 200 and 250° C. Alternatively, thehydrothermal carbonization can be carried out at higher temperatures,for example, between 200 and 800° C., for example, between 300 and 700°C., for example between 400 and 600° C. In some embodiments, thehydrothermal carbonization can be carried out at a temperature andpressure to achieve graphitic structures. The range of pressuressuitable for conducting the hydrothermal carbonization are known in theart, and the pressure can vary, for example, increase, over the courseof the reaction. The pressure for hydrothermal carbonization can varyfrom 0.1 MPa to 200 MPA. In certain embodiments the pressure ofhydrothermal carbonization is between 0.5 MPa and 5 MPa. In otherembodiments, the pressure of hydrothermal carbonization is between 1 MPaand 10 MPa, or between 5 and 20 MPa. In yet other embodiments, thepressure of hydrothermal carbonization is between 10 MPa and 50 MPa. Inyet other embodiments, the pressure of hydrothermal carbonization isbetween 50 MPa and 150 MPa. In yet other embodiments, the pressure ofhydrothermal carbonization is between 100 MPa and 200 MPa. Feedstocksuitable as carbon source for hydrothermal carbonization are also knownin the art. Such feedstocks for hydrothermal carbonization typicallycomprise carbon and oxygen, these include, but are not limited to,sugars, oils, biowastes, polymers, and polymer precursors describedelsewhere within this disclosure.

Accordingly, the present disclosure provides for the manufacturing of acomposite silicon-carbon material, wherein the carbon scaffold materialis a porous carbon material, and wherein the silicon impregnation isachieved by contacting with a silicon-containing reactant, and wherein aterminal carbon coating is achieved by hydrothermal carbonization. Forexample, the process may involve the following steps:

-   -   a) mixing polymer(s) and/or polymer precursor(s) and storing for        a period of time at sufficient temperature to allow for        polymerization of the precursors,    -   b) carbonization of the resulting polymer material to create a        porous carbon material    -   c) subjecting the porous carbon material to elevated temperature        in the presence of a silicon-containing reactant within a static        or agitated reactor, resulting in a silicon-impregnated carbon        material    -   d) subjecting the silicon impregnated carbon material to        hydrothermal carbonization to yield a composite comprising the        silicon impregnated carbon materials terminally carbon coated        via hydrothermal carbonization. suspending particles of a        silicon alloy in a liquid medium containing

Without being bound by theory, it is important that surface of thecarbon particle need to achieve the desired temperature to achieve thedesired extent of reaction and deposition with the silicon-containinggas. Conventional engineering principles dictate that it is difficult toheat the interior vs the exterior of the particle, for example theparticle heats from the outside surface via convective heating (orperhaps other mechanism such as, but not limited to, microwaves orradiative heating), and then the temperature within the particle heatsvia conductive heating from the outside of the carbon particle to theinside. It is non-obvious that in the case of a porous particle, theinside of the particle heats concomitantly with the outside, providedthat the inside comprises surface area with equal access to the gasmolecules that are colliding with the carbon on the particle surface andimparting heat via convection.

Without being bound by theory, the reaction condition may be such thatthe mean free path length of the silicon-containing gas is similar orlower than the diameter and/or the depths of pores that are desired tobe filled. Such a case is known in the art as controlled by Knudsendiffusion, i.e., a means of diffusion that occurs when the scale lengthof a system is comparable to or smaller than the mean free path of theparticles involved. Consider the diffusion of gas molecules through verysmall capillary pores. If the pore diameter is smaller than the meanfree path of the diffusing gas molecules and the density of the gas islow, the gas molecules collide with the pore walls more frequently thanwith each other. This process is known as Knudsen flow or Knudsendiffusion. The Knudsen number is a good measure of the relativeimportance of Knudsen diffusion. A Knudsen number much greater than oneindicates Knudsen diffusion is important. In practice, Knudsen diffusionapplies only to gases because the mean free path for molecules in theliquid state is very small, typically near the diameter of the moleculeitself. In cases where the pore diameter is much greater than the meanfree path length of the gas, the diffusion is characterized as Fiskdiffusion.

The process can be varied for the deposition process, for example can beambient, or about 101 kPa. In certain embodiments, the pressure can beless than ambient, for example less than 101 kPa, for example less than10.1 kPa, for example less than 1.01 kPa. In certain embodiments, thegas comprises a mixture of the silicon-containing deposition gas and aninert gas, for example a combination of silane and nitrogen. In thiscase the partial pressure of the deposition gas can be less than 101kPa, for example less than 10.1 kPa, for example less than 1.01 kPa. Incertain embodiments, the pressure and temperature are such that thesilicon-containing gas is supercritical.

Accordingly, in certain embodiments, the silicon-containing reactant canbe supercritical silane, for example silane at a temperature above about270 K (−3 C) and a pressure above about 45 bar. In further embodiments,the silicon-containing reactant can be supercritical silane, for examplesilane at a temperature between 0-100° C. and a pressure between 45 and100 bar. In further embodiments, the silicon-containing reactant can besupercritical silane, for example silane at a temperature between100-600° C. and a pressure between 45 and 100 bar. In furtherembodiments, the silicon-containing reactant can be supercriticalsilane, for example silane at a temperature between 300-500° C. and apressure between 50 and 100 bar. In further embodiments, thesilicon-containing reactant can be supercritical silane, for examplesilane at a temperature between 400-550° C. and a pressure between 50and 80 bar.

In certain embodiments, the pressure and temperature are both variedover the time within the process of silicon impregnation of the porouscarbon scaffold. For example, the porous carbon scaffold can be held ata certain temperature and pressure, for example at temperature at orhigher than ambient, and at a pressure less than ambient. In this case,the combination of low pressure and high temperature allows fordesorption of volatile components that could potential clog or otherwiseoccupy the porous within the porous carbon scaffold, thus facilitatingthe access of the silicon-containing reactant. Examples of temperaturepressure conditions include, for example, 50-900° C. and 0.1 to 101 kPa,and various combinations thereof. These conditions can be employed as afirst step in the absence of silicon-containing reactant, followed asecond condition of temperature and pressure in the presence of thesilicon-containing reactant. Examples of temperature and pressure rangesfor the latter are found throughout this disclosure.

The CVD process can be accomplished via various modes according to theart. For example, the CVD can be carried out in a static mode, whereinthe particles are not agitated, and the CVD gas flows over, around, orotherwise permeates the particles to be coated. In other exemplarymodes, the particles can be fluidized, for example CVD can be carriedout in a fluidized bed reactor. A variety of different reactor designscan be employed in this context as known in the art, including, but notlimited to, elevator kiln, roller hearth kiln, rotary kiln, box kiln,and fluidized bed designs. These designs can be combined with varioussilicon-containing gases to be employed as a deposition gas, including,but not limited to, silane, disilane, trisilane, tetrasilane,chlorosilane, dichlorosilane, trichlorosilane, and tetrachlorosilane.

In the case of a rotary kiln, various methods for facilitating theproper dispersion and tumbling of particles within the reactor are knownin art, and provide maximal contacting of the porous carbon and thesilicon-containing reactant. These methods include equipmentmodifications such as lifters, helical flights, various screw/impellordesigns and the like. Also known in the art are strategies to load therotary kiln with additional, non-reactive particles to facilitatedispersion and minimum agglomeration of the porous carbon scaffoldparticles.

The CVD process can also employ microwaves to achieve heating the carbonparticles to be processed. Accordingly, the above reactor configurationscan also be combined with microwaves as part of the processing,employing engineering design principles known in the art. Without beingbound by theory, carbon particle are efficient microwave absorbers and areactor can be envisioned wherein the particles are subjected tomicrowaves to heat them prior to introduction of the silicon-containinggas to be deposited to the particles.

E. Dielectric Heating

Dielectric heating is the process in which a high-frequency alternatingelectric field, or radio wave or microwave electromagnetic radiationheats a dielectric material. Molecular rotation occurs in materialscontaining polar molecules having an electrical dipole moment, with theconsequence that they will align themselves in an electromagnetic field.If the field is oscillating, as it is in an electromagnetic wave or in arapidly oscillating electric field, these molecules rotate continuouslyby aligning with it. This is called dipole rotation, or dipolarpolarization. As the field alternates, the molecules reverse direction.Rotating molecules push, pull, and collide with other molecules (throughelectrical forces), distributing the energy to adjacent molecules andatoms in the material. Once distributed, this energy appears as heat.

Temperature is related to the average kinetic energy (energy of motion)of the atoms or molecules in a material, so agitating the molecules inthis way increases the temperature of the material. Thus, dipolerotation is a mechanism by which energy in the form of electromagneticradiation can raise the temperature of an object. Dipole rotation is themechanism normally referred to as dielectric heating, and is most widelyobservable in the microwave oven where it operates most efficaciously onliquid water, and also, but much less so, on fats and sugars, and othercarbon-comprising materials.

Dielectric heating involves the heating of electrically insulatingmaterials by dielectric loss. A changing electric field across thematerial causes energy to be dissipated as the molecules attempt to lineup with the continuously changing electric field. This changing electricfield may be caused by an electromagnetic wave propagating in free space(as in a microwave oven), or it may be caused by a rapidly alternatingelectric field inside a capacitor. In the latter case, there is nofreely propagating electromagnetic wave, and the changing electric fieldmay be seen as analogous to the electric component of an antenna nearfield. In this case, although the heating is accomplished by changingthe electric field inside the capacitive cavity at radio-frequency (RF)frequencies, no actual radio waves are either generated or absorbed. Inthis sense, the effect is the direct electrical analog of magneticinduction heating, which is also near-field effect (thus not involvingradio waves).

Frequencies in the range of 10-100 MHz are necessary to cause efficientdielectric heating, although higher frequencies work equally well orbetter, and in some materials (especially liquids) lower frequenciesalso have significant heating effects, often due to more unusualmechanisms. Dielectric heating at low frequencies, as a near-fieldeffect, requires a distance from electromagnetic radiator to absorber ofless than ½π≈⅙ of a wavelength. It is thus a contact process ornear-contact process, since it usually sandwiches the material to beheated (usually a non-metal) between metal plates taking the place ofthe dielectric in what is effectively a very large capacitor. However,actual electrical contact is not necessary for heating a dielectricinside a capacitor, as the electric fields that form inside a capacitorsubjected to a voltage do not require electrical contact of thecapacitor plates with the (non-conducting) dielectric material betweenthe plates. Because lower frequency electrical fields penetratenon-conductive materials far more deeply than do microwaves, heatingpockets of water and organisms deep inside dry materials like wood, itcan be used to rapidly heat and prepare many non-electrically conductingfood and agricultural items, so long as they fit between the capacitorplates. At very high frequencies, the wavelength of the electromagneticfield becomes shorter than the distance between the metal walls of theheating cavity, or than the dimensions of the walls themselves. This isthe case inside a microwave oven. In such cases, conventional far-fieldelectromagnetic waves form (the cavity no longer acts as a purecapacitor, but rather as an antenna), and are absorbed to cause heating,but the dipole-rotation mechanism of heat deposition remains the same.However, microwaves are not efficient at causing the heating effects oflow frequency fields that depend on slower molecular motion, such asthose caused by ion-drag.

Microwave heating is a sub-category of dielectric heating at frequenciesabove 100 MHz, where an electromagnetic wave can be launched from asmall dimension emitter and guided through space to the target. Modernmicrowave ovens make use of electromagnetic waves with electric fieldsof much higher frequency and shorter wavelength than RF heaters. Typicaldomestic microwave ovens operate at 2.45 GHz, but 915 MHz ovens alsoexist. This means that the wavelengths employed in microwave heating are12 or 33 cm (4.7 or 13.0 in). This provides for highly efficient, butless penetrative, dielectric heating. Although a capacitor-like set ofplates can be used at microwave frequencies, they are not necessary,since the microwaves are already present as far field typeelectromagnetic radiation, and their absorption does not require thesame proximity to a small antenna, as does RF heating. The material tobe heated (a non-metal) can therefore simply be placed in the path ofthe waves, and heating takes place in a non-contact process.

Microwave absorbing materials are thus capable of dissipating anelectromagnetic wave by converting it into thermal energy. Without beingbound by theory, a material's microwave absorption capacity is mainlydetermined by its relative permittivity, relative permeability, theelectromagnetic impedance match, and the material microstructure, forexample its porosity and/or nano- or micro-structure. When a beam ofmicrowave irradiates the surface of an microwave absorbing material, asuitable matching condition for the electromagnetic impedance can enablealmost zero reflectivity of the incident microwave, ultimately resultingin transfer of thermal energy to the absorbing material.

F. Microwave Heating of Carbon Materials

Carbon materials are capable of absorbing microwaves, i.e., they areeasily heated by microwave radiation, i.e., infrared radiation andradiowaves in the region of the electromagnetic spectrum. Morespecifically, they are defined as those waves with wavelengths between0.001 and 1 m, which correspond to frequencies between 300 and 0.3 GHz.The ability of carbon to be heated in the presence of a microwave field,is defined by its dielectric loss tangent: tan δ=∈″/∈′. The dielectricloss tangent is composed of two parameters, the dielectric constant (orreal permittivity), ∈′, and the dielectric loss factor (or imaginarypermittivity), ∈″; i.e., ∈=∈′−i∈″, where ∈ is the complex permittivity.The dielectric constant (∈′) determines how much of the incident energyis reflected and how much is absorbed, while the dielectric loss factor(∈″) measures the dissipation of electric energy in form of heat withinthe material. For optimum microwave energy coupling, a moderate value of∈′ should be combined with high values of ∈″ (and so high values oftans), to convert microwave energy into thermal energy. Thus, while somematerials do not possess a sufficiently high loss factor to allowdielectric heating (transparent to microwaves), other materials, e.g.some inorganic oxides and most carbon materials, are excellent microwaveabsorbers. On the other hand, electrical conductor materials reflectmicrowaves. For example, graphite and highly graphitized carbons mayreflect a considerable fraction of microwave radiation. In the case ofcarbons, where delocalized π-electrons are free to move in relativelybroad regions, an additional and very interesting phenomenon may takeplace. The kinetic energy of some electrons may increase enabling themto jump out of the material, resulting in the ionization of thesurrounding atmosphere. At a macroscopic level, this phenomenon isperceived as sparks or electric arcs formation. But, at a microscopiclevel, these hot spots are actually plasmas. Most of the time theseplasmas can be regarded as microplasmas both from the point of view ofspace and time, since they are confined to a tiny region of the spaceand last for just a fraction of a second. An intensive generation ofsuch microplasmas may have important implications for the processesinvolved.

Without being bound by theory, heating of carbon materials by microwaveheating offers a number of advantages over conventional heating such as:(i) non-contact heating; (ii) energy transfer instead of heat transfer;(iii) rapid heating; (iv) selective material heating; (v) volumetricheating; (vi) quick start-up and stopping; (vii) heating from theinterior of the material body; and, (viii) higher level of safety andautomation [3]. The high capacity of carbon materials to absorbmicrowave energy and convert it into heat is illustrated in Table 1(provided from the reference J. A. Menendez, A. Arenillas, B. Fidalgo,Y. Fernandez, L. Zubizarreta, E. G. Calvo, J. M. Bermudez, “Microwaveheating processes involving carbon materials”, Fuel ProcessingTechnology, 2010, 91 (1), 1-8), where the dielectric loss tangents ofexamples of different carbons are listed. As can be seen, the losstangents of most of the carbons, except for coal, are higher than theloss tangent of distilled water (tans of distilled water=0.118 at 2.45GHz and room temperature).

TABLE 1 Examples of dielectric loss tangents for different carbonmaterials at a frequency of 2.45 GHz and room temperature. Carbon Typetanδ = ε″/ε′ Coal 0.02-0.08 Carbon foam 0.05-0.20 Charcoal 0.11-0.29Carbon black 0.35-0.83 Activated carbon 0.22-2.95 Carbon nanotubes0.25-1.14

Given the potential for carbons to absorb microwaves, there is also apotential for microwave enhancement of carbon-catalyzed reactions, orreactions that occur on or within a carbon particle. Without being boundby theory, there are at least two scenarios where microwaves enhancesuch a reaction on or within a carbon particle: (i) reactions whichrequire a high temperature, and (ii) reactions involving chemicalcompounds which, like the organic compounds, have a low dielectric lossand do not heat up sufficiently under microwave irradiation. Withregards to the current invention, the carbon material acts as bothreaction surface (e.g., catalyst) and microwave receptor.

G. Production of Silicon-Carbon Composites by Microwave-EnabledDecomposition of Silicon Containing Moieties on Porous Carbon Substrate

This invention describes a method for synthesizing a composite materialfrom one or more microwave-absorbing material(s), where saidmicrowave-absorbing material(s) are heated by exposure to microwaveradiation, and introduced to one or more additional feedstockmaterial(s) that thermally decompose on or within pores of the microwaveheated material(s). In preferred embodiments, the microwave heatedmaterial is porous, for example, contains micropores, mesopore, ormacropores, or combinations thereof. In preferred embodiments, theporous, inductively heated material is a carbon material. The porous,microwave heated carbon material may be inherently capable of absorbingmicrowaves, or may be doped with species that otherwise result in thedoped material being capable to absorb microwaves. Heating the poroussubstrate material by microwaves allows for localized heating of thesubstrate particles, without directly heating other materials within thereactor system, for example the material container, the reactor walls,and the atmosphere (gas) within the reactor. This localized heating, inturn, allows for highly efficient, and highly localized decomposition ofa silicon-containing reactant feedstock. Suitable reactant feedstocks inthis regard include, but are not limited to, silicon-containing gasesand silicon-containing liquids. In a preferred embodiment, thesilicon-containing feedstock is silane gas. Accordingly, the methodsdisclosed herein provide advantages to producing homogenoussilicon-composite particles.

In general terms, the current invention is directed to compositematerials wherein silicon is deposited into the pore volume of a porousscaffold material that is a microwave absorbing material. The porous,microwave absorbing scaffold material can comprise a variety ofdifferent materials. In certain preferred embodiments, the porousscaffold material is porous carbon material comprising micropore,mesopore, and/or macropores. Specifically, the porous carbon materialprovides pores in the range of 5 to 1000 nm, which are subsequentlyfilled with silicon. Accordingly, this disclosure also concerns methodsfor manufacturing composite materials wherein silicon is deposited intothe pore volume of a porous scaffold material. A schematic of theprocess is presented in FIG. 1. The resulting composites exhibitremarkably durable intercalation of lithium, and therefore provideoptimized lithium storage and utilization properties. These novelcomposites find utility in any number of electrical energy storagedevices, for example as electrode material in lithium-based electricalenergy storage devices (e.g., lithium ion batteries). Electrodescomprising the novel composites disclosed herein display high reversiblecapacity, high first cycle efficiency, high power performance or anycombination thereof. The present inventors have discovered that suchimproved electrochemical performance is related to the size of thesilicon, the integrity of the silicon and carbon material duringcycling, formation of a stable SEI layer, the physicochemical propertiesof the scaffold materials, for example the surface area and pore volumecharacteristics of the carbon scaffold, and other properties, as well asthe approaches used to manufacture and compound the materials.

Accordingly, in one embodiment, the present disclosure provides for themanufacturing of a novel composite material with durable intercalationof lithium, wherein the composite comprises a porous scaffold andsilicon. For example, the process may involve the following steps:

-   -   a) Creation of a microwave absorbing, porous scaffold material,        wherein the said microwave absorbing porous scaffold material        comprises pore volume in the range of 5 to 1000 nm;    -   b) Heating of the microwave absorbing porous scaffold material        by microwaves in the presence of a silicon-containing feedstock        to a sufficient temperature to enable decomposition of the        silicon-containing feedstock, resulting in a silicon-impregnated        carbon material.

Accordingly, in one embodiment, the present disclosure provides for themanufacturing of a novel composite material with durable intercalationof lithium, wherein the composite comprises carbon and silicon. Forexample, the process may involve the following steps:

-   -   a) Mixing polymer precursors materials and storing for a period        of time at sufficient temperature to allow for polymerization of        the precursors;    -   b) Carbonization of the resulting polymer material to create a        microwave absorbing porous carbon material comprising pore        volume in the range of 5 to 1000 nm;    -   c) Heating of the microwave absorbing porous carbon material by        microwaves in the presence of a silicon-containing feedstock to        a sufficient temperature to enable decomposition of the        silicon-containing feedstock, resulting in a silicon-impregnated        carbon material.

In an alternative embodiment, the present disclosure provides for themanufacturing of a novel composite material with durable intercalationof lithium, wherein the composite comprises a carbon doped with amicrowave absorbing material and silicon. For example, the process mayinvolve the following steps:

-   -   a) Mixing polymer precursors materials and storing for a period        of time at sufficient temperature to allow for polymerization of        the precursors;    -   b) Carbonization of the resulting polymer material to create a        porous carbon material comprising pore volume in the range of 5        to 1000 nm;    -   c) Doping of the porous carbon material with a material capable        of microwave heating;    -   d) Heating of the resulting microwave absorbing porous carbon        material by microwaves in the presence of a silicon-containing        feedstock to a sufficient temperature to enable decomposition of        the silicon-containing feedstock, resulting in a        silicon-impregnated carbon material.

In a related alternative embodiment, the present disclosure provides forthe manufacturing of a novel composite material with durableintercalation of lithium, wherein the composite comprises a carbonproduced from a polymer material comprising a microwave absorbingmaterial and silicon. For example, the process may involve the followingsteps:

-   -   a) Mixing polymer precursors materials in the presence of a        microwave absorbing material and storing for a period of time at        sufficient temperature to allow for polymerization of the        precursors;    -   b) Carbonization of the resulting polymer material to create a        porous microwave absorbing carbon material comprising pore        volume in the range of 5 to 1000 nm;    -   c) Heating of the microwave absorbing porous carbon material by        microwaves in the presence of a silicon-containing feedstock to        a sufficient temperature to enable decomposition of the        silicon-containing feedstock, resulting in a silicon-impregnated        carbon material.

Accordingly, in one embodiment, the present disclosure provides for themanufacturing of a novel composite material with durable intercalationof lithium, wherein the composite comprises a layer of carbonsurrounding the silicon-impregnated carbon material. For example, theprocess may involve the following steps:

-   -   a) Mixing polymer precursors materials and storing for a period        of time at sufficient temperature to allow for polymerization of        the precursors;    -   b) Carbonization of the resulting polymer material to create a        microwave absorbing porous carbon material comprising pore        volume in the range of 5 to 1000 nm;    -   c) Heating of the microwave absorbing porous scaffold material        by microwaves in the presence of a silicon-containing feedstock        to a sufficient temperature to enable decomposition of the        silicon-containing feedstock, resulting in a silicon-impregnated        carbon material;    -   d) Applying a carbon layer on the silicon-impregnated carbon        material to yield a carbon-coated, silicon-impregnated carbon        material.

Accordingly, in one embodiment, the present disclosure provides for themanufacturing of a novel composite material with durable intercalationof lithium, wherein the composite comprises a layer of conductivepolymer surrounding the silicon-impregnated carbon material. Forexample, the process may involve the following steps:

-   -   a) Mixing polymer precursors materials and storing for a period        of time at sufficient temperature to allow for polymerization of        the precursors;    -   b) Carbonization of the resulting polymer material to create a        microwave absorbing porous carbon material comprising pore        volume in the range of 5 to 1000 nm;    -   c) Heating of the microwave absorbing porous scaffold material        by microwaves in the presence of a silicon-containing feedstock        to a sufficient temperature to enable decomposition of the        silicon-containing feedstock, resulting in a silicon-impregnated        carbon material;    -   d) Applying conductive polymer around the silicon-impregnated        carbon material to yield a silicon-impregnated carbon material        further embedded within a conductive polymer network.

Accordingly, the present disclosure provides both novel compositions ofmatter in addition to manufacturing methods thereof, wherein saidmaterials exhibit remarkably durable intercalation of lithium whenincorporated into an electrode of a lithium based energy storage device.In some embodiments, the lithium based electrical energy storage deviceis a lithium ion battery or lithium ion capacitor.

H. Coating of Composite Materials with Conductive Polymer Materials

The composite material comprising a porous silicon material may includevarious surface treatment or properties in order to further improve theelectrochemical performance as defined by capacity, stability and powerperformance. In one embodiment the composite is covered by an ionicallyconductive polymer with a thickness between 1 nm and 10 microns. Inanother embodiment the composite is covered by a ceramic protectivecoating with a thickness between 1 nm and 10 microns. In yet anotherembodiment the composite is covered by an organic film with a thicknessbetween 1 nm and 10 microns. The thickness can be measured with avariety of techniques known in the art such as but not limited to XPSsputtering, FIB/SEM or SIMS.

The composite material can be coated with an ionically conductivepolymer. Example materials include, but are not limited to,polyanaline-based materials, polypyrrole-based materials, a combinationof the two such as poly-pyrrol-co-aniline, polythiophene-basedmaterials, oligomers, PEDOT-PSS, polyvinylidene fluoride and othervinylenes and fluorides, neoprene, silicone, urethane, styrene-butadienerubber-based materials and other rubbers such as isoprene.

The composite material can be coated with a ceramic protective coating.Coating materials include, but are not limited to, oxide-type coatingssuch as alumina, titania, zirconia, and chromium-oxide. Coating materialcan also be non-oxygen containing, such as carbides, nitrides, boridesand silicides. The purpose of the ceramic is to protect the surface ofthe composite material.

The composite material can be coated by an organic material. Organicmaterials could be found in nature or synthetically synthesized.Examples of organic coating materials include, but are not limited to,lignin, cellulose, chitosan, polysaccharides, and lipids.

The act of coating of particles can easily be achieved by those skilledin the art. Commonly employed methods include vapor deposition methodssuch as atomic layer deposition, chemical vapor deposition, andplasma-assisted deposition, physical vapor deposition, sputteringmethods, spray drying, emulsion, spin coating, electrodeposition, anddirect-to-particle selective growth through seeding or other means.

The coating on the composite material is meant to prevent corrosion aswell as provide mechanical stability during expansion and contraction.To this end, the hardness and the elasticity of the material is vital.These values for hardness and elasticity can be measured using methodsknown in the art. Depending on the choice of material, the Mohs hardnessof the coating can range between 0 and 10. Not bound by theory, the Mohshardness of the coating can range between 0 and 5, 0 and 4, 0 to 3, 0 to2, and 0 to 1. In another example, the Mohs hardness of the coating canrange from 5 to 10, 6 to 10, 7 to 10, 8 to 10, and 9 to 10. In limitedcases, the coating may exhibit unusually high Mohs hardness>10. Notbound by theory, the hardness can also be measured using the Vickersscale, rather than the Mohs scale.

In yet another embodiment, the Young's modulus of the coating can bemeasured between 0 and 1210 GPa. In one embodiment, the Young's modulusof the coating is between 0.01 to 11 GPa, 0.01 to 5 GPa, 0.01 to 2 GPa,0.01 to 0.5 GPa, 0.01 to 0.1 GPa, and 1 to 4 GPa. In another example theYoung's modulus of the coating can be greater than 11. The Young'smodulus may be between 11 to 1000 GPa, 20 to 1000 GPa, 50 to 1000 GPa,100 to 1000 GPa, 200 to 1000 GPa, and 400 to 700 GPa.

The thickness of the coating can alter the performance of the compositematerial and may be directly linked to the physical properties of thecoating. In one embodiment the thickness of the coating is between 1 nmand 10 microns, between 1 nm and 5 microns, between 1 nm and 1 micron,between 1 nm and 50 nm. In another embodiment the thickness of thecoating is between 5 microns and 10 microns. In yet another embodiment,the coating is a single atomic monolayer.

The mass of the coating with respect to the mass of the compositeparticle can vary depending on the properties of both the coating andthe composite particle. Not bound by theory, the ratio of the mass ofthe coating to the mass of the composite particle can alter thegravimetric and volumetric capacity of the material. In this embodiment,the mass of the composite particle refers to any and all materials whichare not considered a conductive polymeric or ceramic coating. In oneembodiment the ratio of the mass of the coating to the mass of thecomposite particle is less than 1:50. In another embodiment the ratio ofthe mass of the coating to the mass of the composite particle is between1:50 and 1:1, 1:50 and 1:5, 1:50 and 1:10, 1:50 and 1:20, 1:20 and 1:30.In still another embodiment the ratio of the mass of the coating to themass of the composite particle exceeds 1:1, indicating that more coatingis present than composite material.

The volume of the coating with respect to the volume of the compositeparticle can vary depending on the properties of both the coating andthe composite particle. Not bound by theory, the ratio of the volume ofthe coating to the volume of the composite particle can alter thegravimetric and volumetric capacity of the material. In this embodiment,the volume of the composite particle refers to any and all materialswhich are not considered a conductive polymeric or ceramic coating. Inone embodiment the ratio of the volume of the coating to the volume ofthe composite particle is less than 1:50. In another embodiment theratio of the volume of the coating to the volume of the compositeparticle is between 1:50 and 1:1, 1:50 and 1:5, 1:50 and 1:10, 1:50 and1:20, 1:20 and 1:30. In still another embodiment the ratio of the volumeof the coating to the volume of the composite particle exceeds 1:1,indicating that more coating is present than composite material.

The oxygen content in coating on the composite material can be less than80%, for example, less than 70%, for example less than 60%, for exampleless than 50%, for example, less than 40%, for example, less than 30%,for example, less than 20%, for example less than 10%. In certainembodiments, the oxygen content in the coating on the composite materialis between 10 and 80%. In certain embodiments, the oxygen content in thecoating on the composite material is between 20 and 70%. In certainembodiments, the oxygen content in the coating on the composite materialis between 30 and 60%. In certain embodiments, the oxygen content in thecoating on the composite material is between 40 and 50%. In yet otherembodiments the oxygen content in the coating on the composite materialis less than 10%.

The nitrogen content in coating on the composite material can be lessthan 50%, for example, less than 30%, for example less than 20%, forexample less than 15%, for example, less than 10%, for example, lessthan 5%, for example, less than 1%, for example less than 0.1%. Incertain embodiments, the nitrogen content in the coating on thecomposite material is between 1 and 30%. In certain embodiments, thenitrogen content in the coating on the composite material is between 1and 20%. In certain embodiments, the nitrogen content in the coating onthe composite material is between 1 and 10%. In certain embodiments, thenitrogen content in the coating on the composite material is between 5and 10%.

In certain embodiments, the conductive polymer is pyrolyzed to achieve apyrolyzed conductive polymer coating. There are various embodimentswhereby the conductive polymer can be added as a second carbon compositewith the composite of nano-featured and/or nano-sized and nano-featuredsilicon impregnated into the carbon scaffold. For example, thesilicon-carbon composite can be suspended in a solvent containingdissolved conductive polymer, the suspension can then be dried as knownin the art. In an alternate embodiment, solid particles of conductivepolymer can be mixed with solid silicon particles, and the mixture ofparticles stored at elevated temperature. In preferred embodiments, thetemperature is near or above the glass transition temperature of thepolymer. In additional preferred embodiments, the temperature is near orabove the softening temperature of the polymer. In additional preferredembodiments, the temperature is near or above the melting temperature ofthe polymer. The elevated temperature may be about 100° C., or about120° C., or about 140° C., or about 160° C., or about 180° C., or about200° C. The pyrolysis can be conducted at elevated temperature as knownin the art, for example at 300° C., or 350° C., or 400° C., or 450° C.,or 500° C., or 600° C., or 700° C., or 800° C. In certain embodiments,the mixture of nano-featured or nano-featured and nano-sized silicon canbe pyrolyzed at 850° C., 900° C., 1000° C., 1050° C., or 1100° C.Exemplary conductive polymers include, but are not limited to,polyacrylonitrile (PAN), polyaniline, polypyrrole, polyacetylene,polyphenylene, polyphenylene sulfide, polythiophene, poly(fluorene)s,polypyrenes, polyazulenes, polynaphthalenes, polycarbazoles,polyindoles, polyazepines, poly(3,4-ethylenedioxythiophene) (PEDOT),poly(p-phenylene sulfide) (PPS), poly(p-phenylene vinylene) (PPV), andmixtures thereof. The ratio of nano-featured or nano-featured andnano-sized silicon to conductive polymer can be varied, for example,from 95:5 to 9:95. In certain embodiments, the ratio of silicon toconductive polymer is 95:5 to 60:40, or 90:10 to 70:30.

In another embodiment, the present disclosure provides for themanufacturing of a composite silicon-carbon material, wherein thesilicon material is a nano-sized silicon material or nano-sized siliconmaterial with nano-sized features that is impregnated within the carbonscaffold according to the methods generally described herein, and theresulting silicon carbon composite is further coating with a secondcarbon coating, wherein the second carbon coating is achieved viaapplication of a conductive polymer. In certain embodiments, theconductive polymer is pyrolyzed to achieve a pyrolyzed conductivepolymer coating. There are various embodiments whereby the conductivepolymer can be composited with the composite of nano-featured and/ornano-sized and nano-featured silicon with the carbon. For example, thesilicon carbon composite can be suspended in a solvent containingdissolved conductive polymer, the suspension can then be dried as knownin the art. In an alternate embodiment, solid particles of conductivepolymer can be mixed with solid silicon carbon composite particles, andthe mixture of particles stored at elevated temperature. In preferredembodiments, the temperature is near or above the glass transitiontemperature of the polymer. In additional preferred embodiments, thetemperature is near or above the softening temperature of the polymer.In additional preferred embodiments, the temperature is near or abovethe melting temperature of the polymer. The elevated temperature may beabout 100° C., or about 120° C., or about 140° C., or about 160° C., orabout 180° C., or about 200° C. The pyrolysis can be conducted atelevated temperature as known in the art, for example at 300° C., or350° C., or 400° C., or 450° C., or 500° C., or 600° C., or 700° C., or800° C. In certain embodiments, the mixture of nano-featured ornano-featured and nano-sized silicon can be pyrolyzed at 850° C., 900°C., 1000° C., 1050° C., or 1100° C. Exemplary conductive polymersinclude, but are not limited to, polyacrylonitrile (PAN), polyaniline,polypyrrole, polyacetylene, polyphenylene, polyphenylene sulfide,polythiophene, poly(fluorene)s, polypyrenes, polyazulenes,polynaphthalenes, polycarbazoles, polyindoles, polyazepines,poly(3,4-ethylenedioxythiophene) (PEDOT), poly(p-phenylene sulfide)(PPS), poly(p-phenylene vinylene) (PPV), and mixtures thereof. The ratioof composite of nano-featured or nano-featured and nano-sized siliconwith carbon to conductive polymer can be varied, for example, from 95:5to 9:95. In certain embodiments, the ratio of composite to conductivepolymer is 95:5 to 60:40, or 90:10 to 70:30.

I. Electrochemical Performance of Composites with Extremely DurableInsertion of Lithium

As noted above, the present disclosure is directed to compositematerials comprising a core of porous carbon scaffold upon which nanosilicon is impregnated or otherwise introduced via CVD in the presenceof silane gas, or other suitable technique, with an optional finalcoating, for example of carbon achieved via CVD in the presence ofpropane, or other suitable technique, or coating with conductivepolymer. Such composites exhibit extremely durable intercalation oflithium, and therefore are highly useful as anode material inlithium-based (or sodium-based) and other electrical storage devices.While not wishing to be bound by theory, it is believed that the nanosized silicon achieved as a result of filling in certain, desired porevolume structure of the porous carbon scaffold (for instance, siliconfilling pores in the range of 5 to 1000 nm, or other range as disclosedelsewhere herein), along with the advantageous properties of the othercomponents of the composite, including the carbon or conductive polymercoating, and, at least in part, owing its preparation method, andvariation of the preparation parameters, yield composite materialshaving different and advantageous properties, for instanceelectrochemical performance when the composite comprises an anode of alithium ion energy storage device.

In certain embodiments, the electrochemical performance of the compositedisclosed herein is tested in a half-cell; alternatively the performanceof the composite with extremely durable intercalation of lithiumdisclosed herein is tested in a full cell, for example a full cell coincell, a full cell pouch cell, a prismatic cell, or other batteryconfigurations known in the art. The anode composition comprising thecomposite with extremely durable intercalation of lithium disclosedherein can further comprise various species, as known in the art.Additional formulation components include, but are not limited to,conductive additives, such as conductive carbons such as Super P,Ketjenblack carbons, and the like, conductive polymers and the like,binders such as styrene-butadiene rubber sodium carboxymethylcellulose(SBR-Na CMC), polyvinylidene difluoride (PVDF), and the like, andcombinations thereof. The various types and species comprising theelectrode are known in the art. The % of active material in theelectrode by weight can vary, for example between 1 and 5%, for examplebetween 5 and 15%, for example between 15 and 25%, for example between25 and 35%, for example between 35 and 45%, for example between 45 and55%, for example between 55 and 65%, for example between 65 and 75%, forexample between 75 and 85%, for example between 85 and 95%. In preferredembodiments, the active material comprises between 80 and 95% of theelectrode. In certain embodiment, the amount of conductive additive inthe electrode can vary, for example between 1 and 5%, between 5 and 15%,for example between 15 and 25%, for example between 25 and 35%. Inpreferred embodiments, the amount of conductive additive in theelectrode is between 5 and 25%. In certain embodiments, the amount ofbinder can vary, for example between 1 and 5%, between 5 and 15%, forexample between 15 and 25%, for example between 25 and 35%. In certainembodiments, the amount of conductive additive in the electrode isbetween 5 and 25%.

The composite with extremely durable intercalation of lithium disclosedherein improves the properties of any number of electrical energystorage devices, for example the composite with extremely durableintercalation of lithium disclosed herein have been shown to improve thefirst cycle efficiency of a lithium-based battery. Accordingly, oneembodiment of the present disclosure provides a composite with extremelydurable intercalation of lithium disclosed herein, wherein said matterhas a first cycle efficiency of greater than 50% when the matter isincorporated into an electrode of a lithium based energy storage device,for example a lithium ion battery. For example, some embodiments providea composite with extremely durable intercalation of lithium disclosedherein having a surface area of greater than 50 m²/g, wherein the carbonmaterial has a first cycle efficiency of greater than 50% and areversible capacity of at least 600 mAh/g when the material isincorporated into an electrode of a lithium based energy storage device.In other embodiments, the first cycle efficiency is greater than 55%. Insome other embodiments, the first cycle efficiency is greater than 60%.In yet other embodiments, the first cycle efficiency is greater than65%. In still other embodiments, the first cycle efficiency is greaterthan 70%. In other embodiments, the first cycle efficiency is greaterthan 75%, and in other embodiments, the first cycle efficiency isgreater than 80%, greater than 90%, greater than 95%, greater than 98%,or greater than 99%.

The silicon-carbon composite material may be prelithiated, as known inthe art. In certain embodiments, the prelithiation is achievedelectrochemically, for example in a half cell, prior to assembling thelithiated anode comprising the porous silicon material into a full celllithium ion battery. In certain embodiments, prelithiation isaccomplished by doping the cathode with a lithium-containing compound,for example a lithium containing salt. Examples of suitable lithiumsalts in this context include, but are not limited to, dilithiumtetrabromonickelate(II), dilithium tetrachlorocuprate(II), lithiumazide, lithium benzoate, lithium bromide, lithium carbonate, lithiumchloride, lithium cyclohexanebutyrate, lithium fluoride, lithiumformate, lithium hexafluoroarsenate(V), lithium hexafluorophosphate,lithium hydroxide, lithium iodate, lithium iodide, lithium metaborate,lithium perchlorate, lithium phosphate, lithium sulfate, lithiumtetraborate, lithium tetrachloroaluminate, lithium tetrafluoroborate,lithium thiocyanate, lithium trifluoromethanesulfonate, lithiumtrifluoromethanesulfonate, and combinations thereof.

The anode comprising the silicon-carbon composite material can be pairedwith various cathode materials to result in a full cell lithium ionbattery. Examples of suitable cathode materials are known in the art.Examples of such cathode materials include, but are not limited toLiCoO₂ (LCO), LiNi_(0.8)Co_(0.15)Al_(0.05)O₂ (NCA),LiNi_(v3)Co_(v3)Mn_(1/3)O₂ (NMC), LiMn₂O₄ and variants (LMO), andLiFePO₄ (LFP).

For the full cell lithium ion battery comprising an anode furthercomprising the silicon-carbon composite material, pairing of cathode toanode can be varied. For example, the ratio of cathode-to-anode capacitycan vary from 0.7 to 1.3. In certain embodiments, the ratio ofcathode-to-anode capacity can vary from 0.7 to 1.0, for example from 0.8to 1.0, for example from 0.85 to 1.0, for example from 0.9 to 1.0, forexample from 0.95 to 1.0. In other embodiments, the ratio ofcathode-to-anode capacity can vary from 1.0 to 1.3, for example from 1.0to 1.2, for example from 1.0 to 1.15, for example from 1.0 to 1.1, forexample from 1.0 to 1.05. In yet other embodiments, the ratio ofcathode-to-anode capacity can vary from 0.8 to 1.2, for example from 0.9to 1.1, for example from 0.95 to 1.05.

For the full cell lithium ion battery comprising an anode furthercomprising the silicon-carbon composite material, the voltage window forcharging and discharging can be varied. In this regard, the voltagewindow can be varied as known in the art, depending on variousproperties of the lithium ion battery. For instance, the choice ofcathode plays a role in the voltage window chosen, as known in the art.Examples of voltage windows vary, for example, in terms of potentialversus Li/Li+, from 2.0 V to 5.0 V, for example from 2.5 V to 4.5V, forexample from 2.5V to 4.2V.

For the full cell lithium ion battery comprising an anode furthercomprising the silicon-carbon composite material, the strategy forconditioning the cell can be varied as known in the art. For example,the conditioning can be accomplished by one or more charge and dischargecycles at various rate(s), for example at rates slower than the desiredcycling rate. As known in the art, the conditioning process may alsoinclude a step to unseal the lithium ion battery, evacuate any gasesgenerated within during the conditioning process, followed by resealingthe lithium ion battery.

For the full cell lithium ion battery comprising an anode furthercomprising the silicon-carbon composite material, the cycling rate canbe varied as known in the art, for example, the rate can between C/20and 20 C, for example between C10 to 10 C, for example between C/5 and 5C. In certain embodiments, the cycling rate is C/10. In certainembodiments, the cycling rate is C/5. In certain embodiments, thecycling rate is C/2. In certain embodiments, the cycling rate is 1 C. Incertain embodiments, the cycling rate is 1 C, with periodic reductionsin the rate to a slower rate, for example cycling at 1 C with a C/10rate employed every 20^(th) cycle. In certain embodiments, the cyclingrate is 2 C. In certain embodiments, the cycling rate is 4 C. In certainembodiments, the cycling rate is 5 C. In certain embodiments, thecycling rate is 10 C. In certain embodiments, the cycling rate is 20 C.

In some embodiments of the foregoing, the composite with extremelydurable intercalation of lithium disclosed herein also comprises asurface area ranging from about 5 m²/g to about 400 m²/g or a porevolume ranging from about 0.05 to about 1.0 cc/g or both. For example,in some embodiments the surface area ranges from about 200 m²/g to about300 m²/g or the surface area is about 250 m²/g.

In certain embodiments, the composite with extremely durableintercalation of lithium disclosed herein has a surface area below 200m²/g, for example below 100 m²/g, for example below 50 m²/g. In furtherembodiments, the composite material has a surface area below 30 m²/g,for instance below 20 m²/g, for instance below 10 m²/g, for instancebelow 5 m²/g, for instance below 2 m²/g, for instance below 1 m²/g.

In other embodiments the composite with extremely durable intercalationof lithium disclosed herein has a surface area of less than 50 m²/g, forexample less than 20 m²/g, for example, less than 10 m²/g, for example,less than 5 m²/g, for example less than 1 m²/g, and wherein the firstcycle efficiency is greater than 50% and the reversible capacity is atleast 600 mAh/g when the material is incorporated into an electrode of alithium based energy storage device. In other embodiments, the firstcycle efficiency is greater than 55%. In some other embodiments, thefirst cycle efficiency is greater than 60%. In yet other embodiments,the first cycle efficiency is greater than 65%. In still otherembodiments, the first cycle efficiency is greater than 70%. In otherembodiments, the first cycle efficiency is greater than 75%, and inother embodiments, the first cycle efficiency is greater than 80%,greater than 90%, greater than 95%, greater than 98%, or greater than99%. In some embodiments of the foregoing, the composite materials alsocomprise a surface area ranging from about 1 m²/g to about 400 m²/g or apore volume ranging from about 0.01 to about 1.0 cc/g or both. Forexample, in some embodiments the surface area ranges from about 200 m²/gto about 300 m²/g or the surface area is about 250 m²/g.

The electrochemical properties of the composite with extremely durableintercalation of lithium disclosed herein (e.g., first cycle efficiency,capacity, etc.) can be determined by incorporating into an electrode,known to those versed in the art. The composite is testedelectrochemically. The methods of testing may vary depending on theelectrode composition, as known in the art. In one example, pure siliconis tested between upper and lower voltages of 1.0V and 10 mV at acurrent of 400 mA/g, after two formation cycles between 1.0V and 70 mVat a current of 200 mA/g, with respect to the mass of the compositematerial. Alternatively, the composite materials are tested by limitingthe capacity at a predefined value and measuring the stability andvoltage fluctuations of the composite.

The first cycle efficiency of the composite with extremely durableintercalation of lithium disclosed herein be determined by comparing thelithium inserted into the anode during the first cycle to the lithiumextracted from the anode on the first cycle, prior prelithiationmodification. When the insertion and extraction are equal, theefficiency is 100%. As known in the art, the anode material can betested in a half-cell, where the counter electrode is lithium metal, theelectrolyte is a 1M LiPF₆ 1:1 ethylene carbonate:diethylcarbonate(EC:DEC), using a commercial polypropylene separator. In certainembodiments, the electrolyte can comprise various additives known toprovide improved performance, such as fluoroethylene carbonate (FEC) orother related fluorinated carbonate compounds, or ester co-solvents suchas methyl butyrate, vinylene carbonate, and other electrolyte additivesknown to improve electrochemical performance of silicon-comprising anodematerials.

Coulombic efficiency can be averaged, for example averaged over cycles 7to cycle 25, when tested in a half cell. In certain embodiments, theaverage efficiency of the composite with extremely durable intercalationof lithium is greater than 0.9, or 90%. In certain embodiments, theaverage efficiency is greater than 0.95, or 95%. In preferredembodiments, the average efficiency is greater than 0.98, or 98%. Infurther preferred embodiments, the average efficiency is greater than0.99, or 99%. In further preferred embodiments, the average efficiencyis greater than 0.991, or 99.1%. In further preferred embodiments, theaverage efficiency is greater than 0.992, or 99.2%. In further preferredembodiments, the average efficiency is greater than 0.993, or 99.3%. Infurther preferred embodiments, the average efficiency is greater than0.994, or 99.4%. In further preferred embodiments, the averageefficiency is greater than 0.995, or 99.5%. In further preferredembodiments, the average efficiency is greater than 0.996, or 99.6%. Infurther preferred embodiments, the average efficiency is greater than0.997, or 99.7%. In further preferred embodiments, the averageefficiency is greater than 0.998, or 99.8%. In further preferredembodiments, the average efficiency is greater than 0.999, or 99.9%. Infurther preferred embodiments, the average efficiency is greater than0.9999, or 99.99%.

In another embodiment the present disclosure provides a compositematerial with extremely durable intercalation of lithium, wherein thecomposite has a volumetric capacity (i.e., reversible capacity)independent of alloying electrochemical modifier of at least 400 mAh/ccwhen the material is incorporated into an electrode of a lithium basedenergy storage device, for example a lithium ion battery. The volumetriccapacity of the composite can be calculated from multiplying the maximumgravimetric capacity (mAh/g) with the pycnometer, skeletal density(g/cc), without the presence of the electrochemical modifier. In otherembodiments, this volumetric capacity is at least 450 mAh/cc. In someother embodiments, the volumetric capacity is at least 500 mAh/cc. Inyet other embodiments, the volumetric capacity is at least 550 mAh/cc.In still other embodiments, the volumetric capacity is at least 600mAh/cc. In other embodiments, the volumetric capacity is at least 650mAh/cc, and in other embodiments, the volumetric capacity is at least700 mAh/cc. In another embodiment, the volumetric capacity of the carboncomponent of the composite is between 700 and 1100 mAh/cc.

In another embodiment the present disclosure provides a compositematerial with extremely durable intercalation of lithium, wherein thecomposite has a volumetric capacity (i.e., reversible capacity) of atleast 800 mAh/cc when the composite material is incorporated into anelectrode of a lithium based energy storage device, for example alithium ion battery. The volumetric capacity of the composite materialscan be calculated from multiplying the maximum gravimetric capacity(mAh/g) with the pycnometer, skeletal density (g/cc) prior toelectrochemical testing. In other embodiments, the volumetric capacityis at least 900 mAh/cc. In some other embodiments, the volumetriccapacity is at least 1000 mAh/cc. In yet other embodiments, thevolumetric capacity is at least 1100 mAh/cc. In still other embodiments,the volumetric capacity is at least 1200 mAh/cc. In other embodiments,the volumetric capacity is at least 1300 mAh/cc, and in otherembodiments, the volumetric capacity is at least 1400 mAh/cc, at least1500 mAh/cc, at least 1600 mAh/cc, at least 1700 mAh/cc, at least 1800mAh/cc or even at least 1900 mAh/cc. In yet other embodiments, thevolumetric capacity is between 2000 and 8000 mAh/cc. In still otherembodiments, the volumetric capacity is between 4000 and 7000 mAh/cc. Insome particular embodiments the composite materials have a volumetriccapacity ranging from about 2500 mAh/cc to about 3500 mAh/cc.

In another embodiment, the present disclosure provides a compositematerial with extremely durable intercalation of lithium, wherein thecomposite has a gravimetric capacity (i.e., reversible capacity)independent of the alloying electrochemical modifier of at least 150mAh/g when the material is incorporated into an electrode of a lithiumbased energy storage device, for example a lithium ion battery. In otherembodiments, the gravimetric capacity is at least 200 mAh/g. In someother embodiments, this gravimetric capacity is at least 300 mAh/g. Inyet other embodiments, the gravimetric capacity is at least 400 mAh/g.In still other embodiments, the gravimetric capacity is at least 500mAh/g. In other embodiments, the gravimetric capacity is at least 600mAh/g, and in other embodiments, the gravimetric capacity is at least700 mAh/g, at least 800 mAh/g, at least 900 mAh/g, at least 1000 mAh/g,at least 1100 mAh/g, at least 1200 mAh/g, at least 1300 mAh/g, at least1400 mAh/g, at least 1600 mAh/g, at least 1800 mAh/g, at least 2000mAh/g, at least 2500 mAh/g, at least 3000 mAh/g, at least 3500 mAh/g. Inyet other embodiments, the gravimetric capacity is between 1200 and 3500mAh/g. In some particular embodiments the composite materials have agravimetric capacity ranging from about 700 mAh/g to about 2000 mAh/g.In some particular embodiments the composite materials have agravimetric capacity ranging from about 1000 mAh/g to about 1500 mAh/g.In some particular embodiments the composite materials have agravimetric capacity ranging from about 550 mAh/g to about 750 mAh/g. Insome particular embodiments the composite materials have a gravimetriccapacity ranging from about 400 mAh/g to about 500 mAh/g. Certainexamples of any of the above composite materials may comprise anelectrochemical modifier as described in more detail below.

J. Physicochemical Properties of Composites with Extremely DurableInsertion of Lithium that Influence Electrochemical Performance

As noted above, traditional lithium based energy storage devicescomprise graphitic anode material. The disadvantages of graphitic carbonare numerous in lithium ion batteries. For one, the graphite undergoes aphase and volume change during battery operation. That is, the materialphysically expands and contracts when lithium is inserted between thegraphene sheets while the individual sheets physically shift laterallyto maintain a low energy storage state. Secondly, graphite has a lowcapacity. Given the ordered and crystalline structure of graphite, ittakes six carbons to store one lithium ion. The structure is not able toaccommodate additional lithium. Thirdly, the movement of lithium ions isrestricted to a 2D plane, reducing the kinetics and the rate capabilityof the material in a battery. This means that graphite does not performwell at high rates where power is needed. This power disadvantage is oneof the limiting factors for using lithium ion batteries in all-electricvehicles.

Accordingly, and without being bound by theory, there are certainphysicochemical properties of the composite materials that allow fortheir extremely durable intercalation of lithium. Exemplary, criticalcharacteristic in this context are silicon content, morphology and sizewithin the composite, as discussed below and throughout this disclosure.

In certain embodiments, the embedded silicon particles embedded withinthe composite comprise nano-sized features. The nano-sized features canhave a characteristic length scale of preferably less than 1 um,preferably less than 300 nm, preferably less than 150 nm, preferablyless than 100 um, preferably less than 50 nm, preferably less than 30nm, preferably less than 15 nm, preferably less than 10 nm, preferablyless than 5 nm.

In certain embodiments, the silicon embedded within the composite isspherical in shape. In certain other embodiments, the porous siliconparticles are non-spherical, for example rod-like, or fibrous instructure. In preferred embodiments, the silicon exists as a layercoating the inside of pores within the porous carbon scaffold. The depthof this silicon layer can vary, for example the depth can between 5 nmand 10 nm, for example between 5 nm and 20 nm, for example between 5 nmand 30 nm, for example between 5 nm and 33 nm, for example between 10 nmand 30 nm, for example between 10 nm and 50 nm, for example between 10nm and 100 nm, for example between 10 and 150 nm, for example between 50nm and 150 nm, for example between 100 and 300 nm, for example between300 and 1000 nm.

In preferred embodiments, the silicon embedded within the composite isnano sized, and resides within pores of the porous carbon scaffold. Forexample, the embedded silicon can be impregnated, deposited by CVD, orother appropriate process into pores within the porous carbon particlecomprising pore sizes between 5 and 1000 nm, for example between 10 and500 nm, for example between 10 and 200 nm, for example between 10 and100 nm, for example between 33 and 150 nm, for example between and 20and 100 nm. Other ranges of carbon pores sizes with regards tofractional pore volume, whether micropores, mesopores, or macropores,are also envisioned.

In certain embodiments, the porous silicon particles embedded within thecomposite fill the pores within the porous carbon scaffold material. Thepercent of pore volume within the porous carbon scaffold that is filledwith silicon can vary. For example, the silicon embedded within theporous carbon scaffold material can occupy between 5% and 15% of thetotal available pore volume within the porous carbon scaffold. In otherembodiments, the silicon embedded within the porous carbon scaffoldmaterial can occupy between 15% and 25% of the total available porevolume within the porous carbon scaffold. In other embodiments, thesilicon embedded within the porous carbon scaffold material can occupybetween 25% and 35% of the total available pore volume within the porouscarbon scaffold. In other embodiments, the silicon embedded within theporous carbon scaffold material can occupy between 20% and 40% of thetotal available pore volume within the porous carbon scaffold. In otherembodiments, the silicon embedded within the porous carbon scaffoldmaterial can occupy between 25% and 50% of the total available porevolume within the porous carbon scaffold. In other embodiments, thesilicon embedded within the porous carbon scaffold material can occupybetween 30% and 70% of the total available pore volume within the porouscarbon scaffold, for example between 30% and 60% of the total availablepore volume within the porous carbon scaffold. In other embodiments, thesilicon embedded within the porous carbon scaffold material can occupybetween 60% and 80% of the total available pore volume within the porouscarbon scaffold. In other embodiments, the silicon embedded within theporous carbon scaffold material can occupy between 80% and 100% of thetotal available pore volume within the porous carbon scaffold.

In preferred embodiments, the silicon embedded within the porous carbonscaffold material occupies a fraction of the total available pore volumewithin the porous carbon scaffold, with the remainder of the pore volumebeing available for the silicon to expand into upon the uptake oflithium. In this context, and without being bound by theory, thisremaining pore volume may or may not be accessible to nitrogen, andtherefore may or may not be observed upon employing nitrogen gassorption as disclosed herein.

Accordingly, in some embodiments, the silicon embedded within the porouscarbon scaffold material can occupy between 30% and 70% of the totalavailable pore volume within the porous carbon scaffold, and thecomposite particle comprising the porous carbon scaffold and theembedded silicon comprised a pore volume of at least 0.01 cm³/g. In someembodiments, the silicon embedded within the porous carbon scaffoldmaterial can occupy between 30% and 70% of the total available porevolume within the porous carbon scaffold, and the composite particlecomprising the porous carbon scaffold and the embedded silicon compriseda pore volume of at least 0.1 cm³/g. In some embodiments, the siliconembedded within the porous carbon scaffold material can occupy between30% and 70% of the total available pore volume within the porous carbonscaffold, and the composite particle comprising the porous carbonscaffold and the embedded silicon comprised a pore volume of at least0.2 cm³/g. In some embodiments, the silicon embedded within the porouscarbon scaffold material can occupy between 30% and 70% of the totalavailable pore volume within the porous carbon scaffold, and thecomposite particle comprising the porous carbon scaffold and theembedded silicon comprised a pore volume of at least 0.4 cm³/g. In someembodiments, the silicon embedded within the porous carbon scaffoldmaterial can occupy between 30% and 70% of the total available porevolume within the porous carbon scaffold, and the composite particlecomprising the porous carbon scaffold and the embedded silicon compriseda pore volume of at least 0.6 cm³/g. In some embodiments, the siliconembedded within the porous carbon scaffold material can occupy between30% and 70% of the total available pore volume within the porous carbonscaffold, and the composite particle comprising the porous carbonscaffold and the embedded silicon comprised a pore volume of at least0.8 cm³/g. In some embodiments, the silicon embedded within the porouscarbon scaffold material can occupy between 30% and 70% of the totalavailable pore volume within the porous carbon scaffold, and thecomposite particle comprising the porous carbon scaffold and theembedded silicon comprised a pore volume of at least 0.8 cm³/g.

Accordingly, in some embodiments, the silicon embedded within the porouscarbon scaffold material can occupy between 30% and 70% of the totalavailable pore volume within the porous carbon scaffold, and thecomposite particle comprising the porous carbon scaffold and theembedded silicon comprised a pore volume of less than 0.5 cm³/g. In someembodiments, the silicon embedded within the porous carbon scaffoldmaterial can occupy between 30% and 70% of the total available porevolume within the porous carbon scaffold, and the composite particlecomprising the porous carbon scaffold and the embedded silicon compriseda pore volume of less than 0.4 cm³/g. In some embodiments, the siliconembedded within the porous carbon scaffold material can occupy between30% and 70% of the total available pore volume within the porous carbonscaffold, and the composite particle comprising the porous carbonscaffold and the embedded silicon comprised a pore volume of less than0.3 cm³/g. In some embodiments, the silicon embedded within the porouscarbon scaffold material can occupy between 30% and 70% of the totalavailable pore volume within the porous carbon scaffold, and thecomposite particle comprising the porous carbon scaffold and theembedded silicon comprised a pore volume of less than 0.2 cm³/g. In someembodiments, the silicon embedded within the porous carbon scaffoldmaterial can occupy between 30% and 70% of the total available porevolume within the porous carbon scaffold, and the composite particlecomprising the porous carbon scaffold and the embedded silicon compriseda pore volume of less than 0.1 cm³/g. In some embodiments, the siliconembedded within the porous carbon scaffold material can occupy between30% and 70% of the total available pore volume within the porous carbonscaffold, and the composite particle comprising the porous carbonscaffold and the embedded silicon comprised a pore volume of less than0.05 cm³/g. In some embodiments, the silicon embedded within the porouscarbon scaffold material can occupy between 30% and 70% of the totalavailable pore volume within the porous carbon scaffold, and thecomposite particle comprising the porous carbon scaffold and theembedded silicon comprised a pore volume of less than 0.02 cm³/g. Insome embodiments, the silicon embedded within the porous carbon scaffoldmaterial can occupy between 30% and 70% of the total available porevolume within the porous carbon scaffold, and the composite particlecomprising the porous carbon scaffold and the embedded silicon compriseda pore volume of less than 0.01 cm³/g.

In certain other embodiments, the silicon embedded within the porevolume of the porous silicon resides substantially within macropores, asevidenced by reduction in macropore volume in the silicon-embeddedcomposite material compared to the porous carbon scaffold material priorto the addition of the silicon. Thus, in some embodiments, the embeddedsilicon results in at least 10% reduction of the macropore volume, forexample at least 20% reduction of the macropore volume, for example atleast 30% reduction of the macropore volume, for example at least 40%reduction of the macropore volume, for example at least 50% reduction ofthe macropore volume, for example at least 60% reduction of themacropore volume, for example at least 70% reduction of the macroporevolume, for example at least 80% reduction of the macropore volume, forexample at least 90% reduction of the macropore volume.

In certain other embodiments, the silicon embedded within the porevolume of the porous silicon resides substantially within mesopores, asevidenced by reduction in mesopore volume in the silicon-embeddedcomposite material compared to the porous carbon scaffold material priorto the addition of the silicon. Thus, in some embodiments, the embeddedsilicon results in at least 10% reduction of the mesopore volume, forexample at least 20% reduction of the mesopore volume, for example atleast 30% reduction of the mesopore volume, for example at least 40%reduction of the mesopore volume, for example at least 50% reduction ofthe mesopore volume, for example at least 60% reduction of the mesoporevolume, for example at least 70% reduction of the mesopore volume, forexample at least 80% reduction of the mesopore volume, for example atleast 90% reduction of the mesopore volume.

In certain other embodiments, the silicon embedded within the porevolume of the porous silicon resides substantially within micropores, asevidenced by reduction in micropore volume in the silicon-embeddedcomposite material compared to the porous carbon scaffold material priorto the addition of the silicon. Thus, in some embodiments, the embeddedsilicon results in at least 10% reduction of the micropore volume, forexample at least 20% reduction of the micropore volume, for example atleast 30% reduction of the micropore volume, for example at least 40%reduction of the micropore volume, for example at least 50% reduction ofthe micropore volume, for example at least 60% reduction of themicropore volume, for example at least 70% reduction of the microporevolume, for example at least 80% reduction of the micropore volume, forexample at least 90% reduction of the micropore volume.

In certain embodiments, the silicon is both embedded within essentiallyall the available pre volume within the porous carbon scaffold particle,and also covers the surface of the particle, this, the silicon loadingcan represent greater than 100% of the total pore volume of the porouscarbon scaffold prior to the addition of the silicon. For example, thesilicon loading in this context can be greater than 105%, for examplegreater than 110%, for example greater than 120%, for example greaterthan 130%, for example greater than 150%, for example greater than 200%.

In certain embodiments, the pore volume distribution of the compositematerial is proved by high resolution transmission electron spectroscopy(HRTEM).

In certain embodiments, the composite material comprises less than 20%micropores, greater than 30% mesopores and greater than 30% macropores.In certain embodiments, the composite material comprises less than 10%micropores, greater than 30% mesopores and greater than 30% macropores.In certain embodiments, the composite material comprises less than 5%micropores, greater than 30% mesopores and greater than 30% macropores.In certain embodiments, the composite material comprises less than 5%micropores, greater than 40% mesopores and greater than 40% macropores.In certain embodiments, the composite material comprises less than 1%micropores, greater than 40% mesopores and greater than 40% macropores.

In certain embodiments, the composite material comprises less than 10%micropores, greater than 70% mesopores and greater than 20% macropores.In certain embodiments, the composite material comprises less than 10%micropores, greater than 20% mesopores and greater than 70% macropores.In certain embodiments, the composite material comprises less than 10%micropores, greater than 10% mesopores and greater than 80% macropores.In certain embodiments, the composite material comprises less than 10%micropores, greater than 80% mesopores and greater than 10% macropores.

In certain embodiments, the composite material comprises less than 5%micropores, greater than 70% mesopores and greater than 20% macropores.In certain embodiments, the composite material comprises less than 5%micropores, greater than 20% mesopores and greater than 70% macropores.In certain embodiments, the composite material comprises less than 5%micropores, greater than 5% mesopores and greater than 80% macropores.In certain embodiments, the composite material comprises less than 5%micropores, greater than 80% mesopores and greater than 10% macropores.

In certain embodiments, the composite material comprises less than 1%micropores, greater than 70% mesopores and greater than 20% macropores.In certain embodiments, the composite material comprises less than 1%micropores, greater than 20% mesopores and greater than 70% macropores.In certain embodiments, the composite material comprises less than 1%micropores, greater than 10% mesopores and greater than 80% macropores.In certain embodiments, the composite material comprises less than 1%micropores, greater than 80% mesopores and greater than 10% macropores.

In certain embodiment, the composite comprises less than 4% micropores,greater than 84% mesopores and less than 13% macropores.

In certain embodiments, the composite comprises a pore volume between0.01 and 0.5, and the pore volume distribution comprises less than 20%micropores, greater than 50% mesopores, and less than 30% macropores. Incertain embodiments, the composite comprises a pore volume between 0.05and 0.4 cm³/g, and the pore volume distribution comprises less than 10%micropores, greater than 60% mesopores, and less than 20% macropores. Incertain embodiments, the composite comprises a pore volume between 0.1and 0.3 cm³/g, and the pore volume distribution comprises less than 5%micropores, greater than 70% mesopores, and less than 15% macropores. Incertain embodiments, the composite comprises a pore volume between 0.1and 0.3 cm³/g, and the pore volume distribution comprises less than 5%micropores, greater than 85% mesopores, and less than 10% macropores.

In preferred embodiments, the silicon is embedded within a fraction ofthe porous carbon scaffold, and the pores are capped with a coating thatsurrounds the composite particle, for example this coating can comprisecarbon or a conductive polymer, as described elsewhere within thisdisclosure. In this context, and without being bound by theory, thispore volume may not accessible to nitrogen and therefore not detectableby nitrogen sorption. However, this resulting void space within thecomposite particle ca be ascertained by other means, for example bymeasuring tap density, or envelope density, for example by pycnometrytechniques.

Accordingly, the composite material with extremely durable intercalationof lithium may comprise silicon embedded within the porous carbonscaffold material between 30% and 70% of the total available pore volumewithin the porous carbon scaffold, and the composite particle comprisesa tap density less than 0.7 g/cm³, for example less than 0.6 g/cm³, forexample less than 0.5 g/cm³, for example less than 0.4 g/cm³, forexample less than 0.3 g/cm³, for example less than 0.2 g/cm³, forexample less than 0.15 g/cm³, for example less than 0.1 g/cm³.

In some embodiments, the composite material with extremely durableintercalation of lithium may comprise silicon embedded within the porouscarbon scaffold material between 30% and 70% of the total available porevolume within the porous carbon scaffold, and the composite particlecomprises a skeletal density as determined by pycnometry less than 2.1g/cm³, for example less than 2.0 g/cm³, for example less than 1.9 g/cm³,for example less than 1.8 g/cm³, for example less than 1.7 g/cm³, forexample less than 1.6 g/cm³, for example less than 1.4 g/cm³, forexample less than 1.2 g/cm³, for example less than 1.0 g/cm³. In certainembodiments, the composite material comprises a skeletal density between1.8 and 2.2 g/cm³, for example between 1.9 and 2.1 g/cm³, for example,between 2.0 and 2.1 g/cm³.

The silicon content within the composite material exhibiting extremelydurable intercalation of lithium can be varied. For example, the siliconcontent within the composite can range from 5 to 95% by weight. Incertain embodiments, the content of silicon within the composite canrange from 10% to 80%, for example, 20% to 70%, for example 30% to 60%,for example 40 to 50%. In some embodiments, the content of siliconwithin the composite can range from 10% to 50%, for example, 20% to 40%,for example 30% to 40%. In other embodiments, the content of siliconwithin the composite can range from 40% to 80%, for example, 50% to 70%,for example 60% to 70%. In specific embodiments, the content of siliconwithin the composite can range from 10% to 20%. In specific embodiments,the content of silicon within the composite can range from 15% to 25%.In specific embodiments, the content of silicon within the composite canrange from 25% to 35%. In specific embodiments, the content of siliconwithin the composite can range from 35% to 45%. In specific embodiments,the content of silicon within the composite can range from 45% to 55%.In specific embodiments, the content of silicon within the composite canrange from 55% to 65%. In specific embodiments, the content of siliconwithin the composite can range from 65% to 75%. In specific embodiments,the content of silicon within the composite can range from 75% to 85%.

Since the total pore volume (as determined by nitrogen gas sorption) maypartially relate to the storage of lithium ions, the internal ionickinetics, as well as the available composite/electrolyte surfacescapable of charge-transfer, this is one parameter that can be adjustedto obtain the desired electrochemical properties.

Accordingly, the surface area and pore volume of the composite materialexhibiting extremely durable intercalation of lithium can be varied. Forexample, the surface area of the composite material exhibiting extremelydurable intercalation of lithium can range between 10 m²/g and 200 m²/g.In certain embodiments, the surface area of the composite can rangebetween 10 m²/g and 100 m²/g, for example between 20 m²/g and 200 m²/g,for example between 20 m²/g and 150 m²/g, for example between 10 m²/gand 100 m²/g. In some embodiments, the surface area of the composite canrange between 20 m²/g and 80 m²/g, for example between 20 m²/g and 70m²/g, for example between 30 m²/g and 70 m²/g, for example between 40m²/g and 60 m²/g.

The pore volume of the composite material exhibiting extremely durableintercalation of lithium can range between 0.01 cm³/g and 0.2 cm³/g. Incertain embodiments, the pore volume of the composite material can rangebetween 0.01 cm³/g and 0.15 cm³/g, for example between 0.01 cm³/g and0.1 cm³/g, for example between 0.01 cm³/g and 0.05 cm³/g.

The pore volume distribution of the composite material exhibitingextremely durable intercalation of lithium can vary, for example the %micropores can comprise less than 30%, for example less than 20%, forexample less than 10%, for example, less than 5%, for example less than4%, for example, less than 3%, for example, less than 2%, for example,less than 1%, for example, less than 0.5%, for example, less than 0.2%,for example, less than 0.1%. In certain embodiments, there is nodetectable micropore volume in the composite material exhibitingextremely durable intercalation of lithium

In some embodiments, the pore volume distribution of the compositeexhibiting extremely durable intercalation of lithium comprises lessthan 30% mesopores, for example less than 20% mesopores, for exampleless than 10% mesopores, for example less than 5% mesopores, for exampleless than 4% mesopores, for example less than 3% mesopores, for exampleless than 2% mesopores, for example less than 1% mesopores, for exampleless than 0.5% mesopores, for example less than 0.2% mesopores, forexample less than 0.1% mesopores. In some embodiments, there is nodetectable mesopore volume in the composite material exhibitingextremely durable intercalation of lithium. In some embodiments, thepore volume distribution of the composite material exhibiting extremelydurable intercalation of lithium comprises more than 50% macropores, forexample more than 60% macropores, for example more than 70% macropores,for example more than 80% macropores, for example more than 90%macropores, for example more than 95% macropores, for example more than98% macropores, for example more than 99% macropores, for example morethan 99.5% macropores, for example more than 99.9% macropores.

Certain embodiments of the pore volume distribution of the compositematerial exhibiting extremely durable intercalation of lithium comprisesa variety of the embodiments of the above several paragraphs. Forexample, the composite material exhibiting extremely durableintercalation of lithium comprises less than 30% micropores, less than30% mesopores, and greater than 50% macropores. In other embodiments,the composite material exhibiting extremely durable intercalation oflithium comprises less than 20% micropores, less than 20% mesopores, andgreater than 70% macropores. In other embodiments, the compositematerial exhibiting extremely durable intercalation of lithium comprisesless than 10% micropores, less than 10% mesopores, and greater than 80%macropores. In other embodiments, the composite material exhibitingextremely durable intercalation of lithium comprises less than 10%micropores, less than 10% mesopores, and greater than 90% macropores. Inother embodiments, the composite material exhibiting extremely durableintercalation of lithium comprises less than 5% micropores, less than 5%mesopores, and greater than 90% macropores. In other embodiments, thecomposite material exhibiting extremely durable intercalation of lithiumcomprises less than 5% micropores, less than 5% mesopores, and greaterthan 95% macropores.

In certain embodiments, the surface layer of the composite materialexhibits a low Young's modulus, in order to absorb volume deformationassociated with the uptake and intercalation of lithium ions, while notfracturing or otherwise providing additional opportunity for new SEIformation. In this context, the surface layer is sufficient to provide acomposite material comprising a Young's modulus less than 100 GPa, forexample less than 10 GPa, for example less than 1 GPa, for example lessthan 0.1 GPa. In certain embodiments, the surface layer of the compositematerial exhibits a low bulk modulus, in order to absorb volumedeformation associated with the uptake and intercalation of lithiumions, while not fracturing or otherwise providing additional opportunityfor new SEI formation. In this context, the surface layer is sufficientto provide a composite material comprising a bulk modulus less than 100GPa, for example less than 10 GPa, for example less than 1 GPa, forexample less than 0.1 GPa.

In certain other embodiments, the surface layer of the compositematerial exhibits a high bulk modulus, in order to restrict volumedeformation associated with the uptake and intercalation of lithiumions, thus avoiding fracturing or otherwise denying additionalopportunity for new SEI formation. In this context, the surface layer issufficient to provide a composite material comprising a bulk modulusgreater than 10 GPa, for example greater than 50 GPa, for examplegreater than 100 GPa, for example greater than 1000 GPa.

In some embodiments, the surface area of the composite materialexhibiting extremely durable intercalation of lithium can be greaterthan 500 m²/g. In other embodiments, the surface area of the compositematerial exhibiting extremely durable intercalation of lithium can beless than 300 m²/g. In some embodiments, the surface area of thecomposite material exhibiting extremely durable intercalation of lithiumis between 200 and 300 m²/g. In some embodiments, the surface area ofthe composite material exhibiting extremely durable intercalation oflithium is between 100 and 200 m²/g. In some embodiments, the surfacearea of the composite material exhibiting extremely durableintercalation of lithium is between 50 and 100 m²/g. In someembodiments, the surface area of the composite material exhibitingextremely durable intercalation of lithium is between 10 and 50 m²/g. Insome embodiments, the surface area of the composite material exhibitingextremely durable intercalation of lithium is less than 10 m²/g. In someembodiments, the surface area of the composite material exhibitingextremely durable intercalation of lithium is less than 5 m²/g. In someembodiments, the surface area of the composite material exhibitingextremely durable intercalation of lithium is less than 2 m²/g. In someembodiments, the surface area of the composite material exhibitingextremely durable intercalation of lithium is less than 1 m²/g. In someembodiments, the surface area of the composite material exhibitingextremely durable intercalation of lithium is less than 0.5 m²/g. Insome embodiments, the surface area of the composite material exhibitingextremely durable intercalation of lithium is less than 0.1 m²/g.

The surface area of the composite material may be modified throughactivation. The activation method may use steam, chemical activation,CO₂ or other gasses. Methods for activation of carbon material are wellknown in the art.

The volumetric and gravimetric capacity can be determined through theuse of any number of methods known in the art, for example byincorporating into an electrode half-cell with lithium metal counterelectrode in a coin cell. The gravimetric specific capacity isdetermined by dividing the measured capacity by the mass of theelectrochemically active carbon materials. The volumetric specificcapacity is determined by dividing the measured capacity by the volumeof the electrode, including binder and conductivity additive. Methodsfor determining the volumetric and gravimetric capacity are described inmore detail in the Examples.

The composite may contain lithium metal, either through doping orthrough electrochemical cycling) in the pores of the composite, forexample pores within the porous carbon within the composite. Lithiumplating within pores is seen as beneficial to both the capacity andcycling stability of the hard carbon. Plating within the pores can yieldnovel nanofiber lithium. In some cases lithium may be plated on theoutside of the particle. External lithium plating is detrimental to theoverall performance as explained in the examples. The presence of bothinternal and external lithium metal may be measured by cutting amaterial using a focused ion beam (FIB) and a scanning electronmicroscope (SEM). Metallic lithium is easily detected in contrast tohard carbon in an SEM. After cycling, and when the material has lithiuminserted below 0V, the material may be sliced and imaged. In oneembodiment the material displays lithium in the micropores. In anotherembodiment the material displays lithium in the mesopores. In stillanother embodiment, the material displays no lithium plating on thesurface of the material. In yet still another embodiment silicon isstored in multiple pore sizes and shapes. The material shape and poresize distribution may uniquely and preferentially promote pore platingprior to surface plating. Ideal pore size for lithium storage isexplained elsewhere within this disclosure.

The particle size distribution of the composite material exhibitingextremely durable intercalation of lithium is important to bothdetermine power performance as well as volumetric capacity. As thepacking improves, the volumetric capacity may increase. In oneembodiment the distributions are either Gaussian with a single peak inshape, bimodal, or polymodal (>2 distinct peaks). The properties ofparticle size of the composite can be described by the DO (smallestparticle in the distribution), Dv50 (average particle size) and Dv100(maximum size of the largest particle). The optimal combined of particlepacking and performance will be some combination of the size rangesbelow.

In one embodiment the Dv0 of the composite material exhibiting extremelydurable intercalation of lithium can range from 1 nm to 5 microns. Inanother embodiment the Dv0 of the composite ranges from 5 nm to 1micron, or 5 nm to 500 nm, or 5 nm to 100 nm, or 10 nm to 50 nm. Inanother embodiment the Dv0 of the composite ranges from 500 nm to 2microns, or 750 nm to 1 micron, or 1 microns to 2 microns. In stillanother embodiments, the Dv0 of the composite ranges from 2 to 5 micronsor even greater than 5 microns. The particle size reduction in the aboveembodiments can be carried out as known in the art, for example by jetmilling in the presence of various gases including air, nitrogen, argon,helium, supercritical steam, and other gases known in the art.

In one embodiment the Dv50 of the composite material exhibitingextremely durable intercalation of lithium range from 5 nm to 20microns. In another embodiment the Dv50 of the composite ranges from 5nm to 1 micron, 5 nm to 500 nm, 5 nm to 100 nm, 10 nm to 50 nm. Inanother embodiment the Dv50 of the composite ranges from 500 to 2microns, 750 nm to 1 micron, 1 microns to 2 microns. In still anotherembodiments, the Dv50 of the composite ranges from 2 to 20 microns, or 3microns to 10 microns, or 4 microns to 8 microns, or greater than 20microns.

In one embodiment, the Dv100 of the composite material exhibitingextremely durable intercalation of lithium can range from 8 nm to 100microns. In another embodiment the Dv100 of the composite ranges from 5nm to 1 micron, 5 nm to 500 nm, 5 nm to 100 nm, 10 nm to 50 nm. Inanother embodiment the Dv100 of the composite ranges from 500 to 2microns, 750 nm to 1 micron, 1 microns to 2 microns. In still anotherembodiment, the Dv100 of the composite ranges from 2 to 100 microns, 5to 50 microns, 8 to 40 microns, 10 to 35 microns, 15 to 30 microns, 20to 30 microns, around 25 microns, greater than 100 microns.

The span (Dv50)/(Dv90−Dv10), wherein Dv10, Dv50 and Dv90 represent theparticle size at 10%, 50%, and 90% of the volume distribution, can bevaried from example from 100 to 10, from 10 to 5, from 5 to 2, from 2 to1; in some embodiments the span can be less than 1. In certainembodiments, the composite comprising carbon and porous silicon materialparticle size distribution can be multimodal, for example, bimodal, ortrimodal.

In still other embodiments the present disclosure provides a compositematerial exhibiting extremely durable intercalation of lithium, whereinwhen the composite material is incorporated into an electrode of alithium based energy storage device the composite material has avolumetric capacity at least 10% greater than when the lithium basedenergy storage device comprises a graphite electrode. In someembodiments, the lithium based energy storage device is a lithium ionbattery. In other embodiments, the composite material has a volumetriccapacity in a lithium based energy storage device that is at least 5%greater, at least 10% greater, at least 15% greater than the volumetriccapacity of the same electrical energy storage device having a graphiteelectrode. In still other embodiments, the composite material has avolumetric capacity in a lithium based energy storage device that is atleast 20% greater, at least 30% greater, at least 40% greater, at least50% greater, at least 200% greater, at least 100% greater, at least 150%greater, or at least 200% greater than the volumetric capacity of thesame electrical energy storage device having a graphite electrode.

The composite material may be prelithiated, as known in the art. Theselithium atoms may or may not be able to be separated from the carbon.The number of lithium atoms to 6 carbon atoms can be calculated bytechniques known to those familiar with the art:

#Li=Q×3.6×MM/(C %×F)

Wherein Q is the lithium extraction capacity measured in mAh/g betweenthe voltages of 5 mV and 2.0V versus lithium metal, MM is 72 or themolecular mass of 6 carbons, F is Faraday's constant of 96500, C % isthe mass percent carbon present in the structure as measured by CHNO orXPS.

The composite material exhibiting extremely durable intercalation oflithium can be characterized by the ratio of lithium atoms to carbonatoms (Li:C) which may vary between about 0:6 and 2:6. In someembodiments the Li:C ratio is between about 0.05:6 and about 1.9:6. Inother embodiments the maximum Li:C ratio wherein the lithium is in ionicand not metallic form is 2.2:6. In certain other embodiments, the Li:Cratio ranges from about 1.2:6 to about 2:6, from about 1.3:6 to about1.9:6, from about 1.4:6 to about 1.9:6, from about 1.6:6 to about 1.8:6or from about 1.7:6 to about 1.8:6. In other embodiments, the Li:C ratiois greater than 1:6, greater than 1.2:6, greater than 1.4:6, greaterthan 1.6:6 or even greater than 1.8:6. In even other embodiments, theLi:C ratio is about 1.4:6, about 1.5:6, about 1.6:6, about 1.6:6, about1.7:6, about 1.8:6 or about 2:6. In a specific embodiment the Li:C ratiois about 1.78:6.

In certain other embodiments, the composite material exhibitingextremely durable intercalation of lithium comprises an Li:C ratioranging from about 1:6 to about 2.5:6, from about 1.4:6 to about 2.2:6or from about 1.4:6 to about 2:6. In still other embodiments, thecomposite materials may not necessarily include lithium, but insteadhave a lithium uptake capacity (i.e., the capability to uptake a certainquantity of lithium, for example upon cycling the material between twovoltage conditions (in the case of a lithium ion half cell, an exemplaryvoltage window lies between 0 and 3 V, for example between 0.005 and 2.7V, for example between 0.005 and 1 V, for example between 0.005 and 0.8V). While not wishing to be bound by theory, it is believed the lithiumuptake capacity of the composite materials contributes to their superiorperformance in lithium based energy storage devices. The lithium uptakecapacity is expressed as a ratio of the atoms of lithium taken up by thecomposite. In certain other embodiments, the composite materialexhibiting extremely durable intercalation of lithium comprise a lithiumuptake capacity ranging from about 1:6 to about 2.5:6, from about 1.4:6to about 2.2:6 or from about 1.4:6 to about 2:6.

In certain other embodiments, the lithium uptake capacity ranges fromabout 1.2:6 to about 2:6, from about 1.3:6 to about 1.9:6, from about1.4:6 to about 1.9:6, from about 1.6:6 to about 1.8:6 or from about1.7:6 to about 1.8:6. In other embodiments, the lithium uptake capacityis greater than 1:6, greater than 1.2:6, greater than 1.4:6, greaterthan 1.6:6 or even greater than 1.8:6. In even other embodiments, theLi:C ratio is about 1.4:6, about 1.5:6, about 1.6:6, about 1.6:6, about1.7:6, about 1.8:6 or about 2:6. In a specific embodiment the Li:C ratiois about 1.78:6.

In certain embodiments, the composite material exhibiting extremelydurable intercalation is doped with an electrochemical modifier, forexample with lithium. Different methods of doping lithium may includechemical reactions, electrochemical reactions, physical mixing ofparticles, gas phase reactions, solid phase reactions, and liquid phasereactions. In other embodiments the lithium is in the form of lithiummetal. As discussed in more detail below, the surface functionality ofthe presently disclosed the composite material exhibiting extremelydurable intercalation of lithium may be altered to obtain the desiredelectrochemical properties. One property which can be predictive ofsurface functionality is the pH of the composite materials. Thepresently disclosed composite materials comprise pH values ranging fromless than 1 to about 14, for example less than 5, from 5 to 8 or greaterthan 8. In some embodiments, the pH of the composite materials is lessthan 4, less than 3, less than 2 or even less than 1. In otherembodiments, the pH of the composite materials is between about 5 and 6,between about 6 and 7, between about 7 and 8 or between 8 and 9 orbetween 9 and 10. In still other embodiments, the pH is high and the pHof the composite materials ranges is greater than 8, greater than 9,greater than 10, greater than 11, greater than 12, or even greater than13.

Pore size distribution of the carbon scaffold may be important to boththe storage capacity of the material and the kinetics and powercapability of the system as well as the ability to incorporate largeamounts of electrochemical modifiers. The pore size distribution canrange from micro- to meso- to macropore sized and may be eithermonomodal, bimodal or multimodal. Micropores, with average pore sizesless than 1 nm, may create additional storage sites as well as lithium(or sodium) ion diffusion paths. Graphite sheets typically are spaced0.33 nm apart for lithium storage. While not wishing to be bound bytheory, it is thought that large quantities of pores of similar size mayyield graphite-like structures within pores with additional hardcarbon-type storage in the bulk structure. Mesopores are typically below100 nm. These pores are ideal locations for nano particle dopants, suchas metals, and provide pathways for both conductive additive andelectrolyte for ion and electron conduction. In some embodiments thecarbon materials comprise macropores greater than 100 nm that may beespecially suited for large particle doping.

Pore size distribution of the composite material exhibiting extremelydurable intercalation of lithium may be important to both the storagecapacity of the material and the kinetics and power capability of thesystem as well as the ability to incorporate large amounts ofelectrochemical modifiers. The pore size distribution can range frommicro to meso to macro and may be either monomodal, bimodal ormultimodal. In some embodiments the composite materials comprisemicropores less than 100 nm which may be especially suited for lithiumdiffusion.

Accordingly, in one embodiment, the composite material comprises afractional pore volume of pores at or below 1 nm that comprises at least50% of the total pore volume, at least 75% of the total pore volume, atleast 90% of the total pore volume or at least 99% of the total porevolume. In other embodiments, the composite material comprises afractional pore volume of pores at or below 10 nm that comprises atleast 50% of the total pore volume, at least 75% of the total porevolume, at least 90% of the total pore volume or at least 99% of thetotal pore volume. In other embodiments, the composite materialcomprises a fractional pore volume of pores at or below 50 nm thatcomprises at least 50% of the total pore volume, at least 75% of thetotal pore volume, at least 90% of the total pore volume or at least 99%of the total pore volume.

In another embodiment, the composite material comprises a fractionalpore surface area of pores at or below 100 nm that comprises at least50% of the total pore surface area, at least 75% of the total poresurface area, at least 90% of the total pore surface area or at least99% of the total pore surface area. In another embodiment, the compositematerial comprises a fractional pore surface area of pores at or greaterthan 100 nm that comprises at least 50% of the total pore surface area,at least 75% of the total pore surface area, at least 90% of the totalpore surface area or at least 99% of the total pore surface area.

In another embodiment, the composite material comprises porespredominantly in the range of 100 nm or lower, for example 10 nm orlower, for example 5 nm or lower. Alternatively, the composite materialcomprises micropores in the range of 0-2 nm and mesopores in the rangeof 2-100 nm. The ratio of pore volume or pore surface in the microporerange compared to the mesopore range can be in the range of 95:5 to5:95.

The present inventors have found that the extent of disorder in thecomposite materials with and without electrochemical modifier may havean impact on the electrochemical properties of the carbon materials.Thus, controlling the extent of disorder in the composite materialsprovides a possible avenue to improve the rate capability for carbonssince a smaller crystallite size may allow for lower resistive lithiumion diffusion through the amorphous structure. The present inventionincludes embodiments which comprise both high and low levels ofdisorder.

Disorder, as recorded by RAMAN spectroscopy, is a measure of the size ofthe crystallites found within both amorphous and crystalline structures(M. A. Pimenta, G. Dresselhaus, M. S. Dresselhaus, L. G. Can ado, A.Jorio, and R. Saito, “Studying disorder in graphite-based systems byRaman spectroscopy,” Physical Chemistry Chemical Physics, vol. 9, no.11, p. 1276, 2007). RAMAN spectra of exemplary carbon are shown in FIG.4. For carbon structures, crystallite sizes (L_(a)) can be calculatedfrom the relative peak intensities of the D and G Raman shifts (Eq. 1)

L _(a)(nm)=(2.4×10⁻¹⁰)λ⁴ _(laser) R ⁻¹  (1)

where

R=I _(D) /I _(G)  (2)

The values for R and L_(a) can vary in certain embodiments, and theirvalue may affect the electrochemical properties of the carbon materials,for example the capacity of the 2^(nd) lithium insertion (2^(nd) lithiuminsertion is related to first cycle efficiency since first cycleefficiency=(capacity at 1^(st) lithium insertion/capacity at 2^(nd)lithium insertion)×100). For example, in some embodiments R ranges fromabout 0 to about 1 or from about 0.50 to about 0.95. In otherembodiments, R ranges from about 0.60 to about 0.90. In otherembodiments, R ranges from about 0.80 to about 0.90. L_(a) also variesin certain embodiments and can range from about 1 nm to about 500 nm. Incertain other embodiments, La ranges from about 5 nm to about 100 nm orfrom about 10 to about 50 nm. In other embodiments, La ranges from about15 nm to about 30 nm, for example from about 20 to about 30 nm or fromabout 25 to 30 nm.

In a related embodiment, the electrochemical properties of materialscomprising the composite are related to the level of crystallinity asmeasured by X-ray diffraction (XRD). While Raman measures the size ofthe crystallites, XRD records the level of periodicity in the bulkstructure through the scattering of incident X-rays. The presentinvention includes materials that are non-graphitic (crystallinity<10%)and semi-graphitic (crystallinity between 10 and 50%). The crystallinityof materials ranges from about 0% to about 99%. In some embodiments, thematerials comprising the composite comprise less than 10% crystallinity,less than 5% crystallinity or even less than 1% crystallinity (i.e.,highly amorphous). In other embodiments, the materials comprising thecomposite comprise from 10% to 50% crystallinity. In still otherembodiments, the materials comprising the composite comprise less than50% crystallinity, less than 40% crystallinity, less than 30%crystallinity or even less than 20% crystallinity.

In a related embodiment, the electrochemical properties of the materialscomprising the composite are related to the level of crystallinity asmeasured by X-ray diffraction (XRD). The present invention includesmaterials that are non-crystalline (crystallinity<10%) andsemi-crystalline (crystallinity between 10 and 50%) and crystalline(>50%). The crystallinity of the materials comprising the compositeranges from about 0% to about 99%. In some embodiments, the materialscomprising the composite comprise less than 10% crystallinity, less than5% crystallinity or even less than 1% crystallinity (i.e., highlyamorphous). In other embodiments, the materials comprising the compositecomprise from 10% to 50% crystallinity. In still other embodiments, thematerials comprising the composite comprise less than 50% crystallinity,less than 40% crystallinity, less than 30% crystallinity or even lessthan 20% crystallinity.

In a related embodiment, the electrochemical performance of thecomposite is related to the empirical values, R, as calculated fromSmall Angle X-ray Diffraction (SAXS), wherein R=B/A and B is the heightof the double layer peak and A is the baseline for the single graphenesheet as measured by SAXS.

SAXS has the ability to measure internal pores, perhaps inaccessible bygas adsorption techniques but capable of lithium storage. In certainembodiments, the R factor is below 1, comprising single layers ofgraphene. In other embodiments, the R factor ranges from about 0.1 toabout 20 or from about 1 to 10. In yet other embodiments, the R factorranges from 1 to 5, from 1 to 2, or from 1.5 to 2. In still otherembodiments, the R factor ranges from 1.5 to 5, from 1.75 to 3, or from2 to 2.5. Alternatively, the R factor is greater than 10. The SAXSpattern may also be analyzed by the number of peaks found between 10°and 40°. In some embodiments, the number of peaks found by SAXS at lowscattering angles are 1, 2, 3, or even more than 3.

In certain embodiments, the organic content of materials comprising thecomposite can be manipulated to provide the desired properties, forexample by contacting the materials with a hydrocarbon compound such ascyclohexane and the like. Infra-red spectroscopy (FTIR) can be used as ametric to determine the organic content of both surface and bulkstructures of the materials. In one embodiment, the materials comprisingthe composite comprise essentially no organic material. An FTIR spectrawhich is essentially featureless is indicative of such embodiments. Inother embodiments, the carbon materials without electrochemical modifiercomprise organic material, either on the surface or within the bulkstructure. In such embodiments, the FTIR spectra generally depict largehills and valleys which indicates the presence of organic content.

The organic content may have a direct relationship to theelectrochemical performance and response of the material when placedinto a lithium bearing device for energy storage. Materials comprisingthe composite with flat FTIR signals (no organics) often display a lowextraction peak in the voltage profile at 0.2 V. Well known to the art,the extract voltage is typical of lithium stripping. In certainembodiments, the materials comprising the composite comprise organiccontent and the lithium stripping plateau is absent or near absent.

The composite material may also comprise varying amounts of carbon,oxygen, hydrogen and nitrogen as measured by gas chromatography CHNOanalysis. In one embodiment, the carbon content of the composite isgreater than 98 wt. % or even greater than 99.9 wt % as measured by CHNOanalysis. In another embodiment, the carbon content of the compositeranges from about 10 wt % to about 99.9%, for example from about 50 toabout 98 wt. % of the total mass. In yet other embodiments, the carboncontent of the composite ranges 90 to 98 wt. %, 92 to 98 wt % or greaterthan 95% of the total mass. In yet other embodiments, the carbon contentof the composite ranges from 80 to 90 wt. % of the total mass. In yetother embodiments, the carbon content of the composite ranges from 70 to80 wt. % of the total mass. In yet other embodiments, the carbon contentranges of the composite from 60 to 70 wt. % of the total mass. In yetother embodiments, the carbon content ranges of the composite from 50 to60 wt. % of the total mass. In yet other embodiments, the carbon contentranges of the composite from 40 to 50 wt. % of the total mass. In yetother embodiments, the carbon content ranges of the composite from 30 to40 wt. % of the total mass. In yet other embodiments, the carbon contentranges of the composite from 20 to 30 wt. % of the total mass. In yetother embodiments, the carbon content ranges of the composite from 10 to20 wt. % of the total mass. In yet other embodiments, the carbon contentranges of the composite from 1 to 10 wt. % of the total mass.

In another embodiment, the nitrogen content ranges from 0 to 90 wt. %based on total mass of all components in the composite material asmeasured by CHNO analysis. In another embodiment, the nitrogen contentranges from 1 to 10 wt. % of the total mass. In yet other embodiments,the nitrogen content ranges from 10 to 20 wt. % of the total mass. Inyet other embodiments, the nitrogen content ranges from 20 to 30 wt. %of the total mass. In another embodiment, the nitrogen content isgreater than 30 wt. %. In some more specific embodiments, the nitrogencontent ranges from about 1% to about 6%, while in other embodiments,the nitrogen content ranges from about 0.1% to about 1%. In certain ofthe above embodiments, the nitrogen content is based on weight relativeto total weight of all components in the composite material

The carbon and nitrogen content may also be measured as a ratio of C:N(carbon atoms to nitrogen atoms). In one embodiment, the C:N ratioranges from 1:0.001 to 0.001:1 or from 1:0.001 to 1:1. In anotherembodiment, the C:N ratio ranges from 1:0.001 to 1:0.01. In yet anotherembodiment, the C:N ratio ranges from 1:0.01 to 1:1. In yet anotherembodiment, the content of nitrogen exceeds the content of carbon, forexample the C:N ratio can range from about 0.01:1 to about 0.1:1 or from0.1:1 to about 0.5:1.

The composite material comprising a silicon material may also comprisevarying amounts of carbon, oxygen, nitrogen, Cl, and Na, to name a few,as measured by XPS analysis. In one embodiment, the carbon content isgreater than 98 wt. % as measured by XPS analysis. In anotherembodiment, the carbon content ranges from 50 to 98 wt. % of the totalmass. In yet other embodiments, the carbon content ranges 90 to 98 wt. %of the total mass. In yet other embodiments, the carbon content rangesfrom 80 to 90 wt. % of the total mass. In yet other embodiments, thecarbon content ranges from 70 to 80 wt. % of the total mass. In yetother embodiments, the carbon content ranges from 60 to 70 wt. % of thetotal mass.

In other embodiments, the carbon content ranges from 10% to 99.9%, from10% to 99%, from 10% to 98%, from 50% to 99.9%, from 50% to 99%, from50% to 98%, from 75% to 99.9%, from 75% to 99% or from 75% to 98% of thetotal mass of all components in the carbon material as measured by XPSanalysis

In another embodiment, the nitrogen content ranges from 0 to 90 wt. % asmeasured by XPS analysis. In another embodiment, the nitrogen contentranges from 1 to 75 wt. % of the total mass. In another embodiment, thenitrogen content ranges from 1 to 50 wt. % of the total mass. In anotherembodiment, the nitrogen content ranges from 1 to 25 wt. % of the totalmass. In another embodiment, the nitrogen content ranges from 1 to 20wt. % of the total mass. In another embodiment, the nitrogen contentranges from 1 to 10 wt. % of the total mass. In another embodiment, thenitrogen content ranges from 1 to 6 wt. % of the total mass. In yetother embodiments, the nitrogen content ranges from 10 to 20 wt. % ofthe total mass. In yet other embodiments, the nitrogen content rangesfrom 20 to 30 wt. % of the total mass. In another embodiment, thenitrogen content is greater than 30 wt. %.

The carbon and nitrogen content may also be measured as a ratio of C:Nby XPS. In one embodiment, the C:N ratio of the composite ranges from0.001:1 to 1:0.001. In one embodiment, the C:N ratio ranges from 0.01:1to 1:0.01. In one embodiment, the C:N ratio ranges from 0.1:1 to 1:0.01.In one embodiment, the C:N ratio ranges from 1:0.5 to 1:0.001. In oneembodiment, the C:N ratio ranges from 1:0.5 to 1:0.01. In oneembodiment, the C:N ratio ranges from 1:0.5 to 1:0.1. In one embodiment,the C:N ratio ranges from 1:0.2 to 1:0.01. In one embodiment, the C:Nratio ranges from 1:0.001 to 1:1. In another embodiment, the C:N ratioranges from 1:0.001 to 0.01. In yet another embodiment, the C:N ratioranges from 1:0.01 to 1:1. In yet another embodiment, the content ofnitrogen exceeds the content of carbon.

The carbon and phosphorus content of the composite may also be measuredas a ratio of C:P by XPS. In one embodiment, the C:P ratio of thecomposite ranges from 0.001:1 to 1:0.001. In one embodiment, the C:Pratio ranges from 0.01:1 to 1:0.01. In one embodiment, the C:P ratioranges from 0.1:1 to 1:0.01. In one embodiment, the C:P ratio rangesfrom 1:0.5 to 1:0.001. In one embodiment, the C:P ratio ranges from1:0.5 to 1:0.01. In one embodiment, the C:P ratio ranges from 1:0.5 to1:0.1. In one embodiment, the C:P ratio ranges from 1:0.2 to 1:0.01. Inone embodiment, the C:P ratio ranges from 1:0.001 to 1:1. In anotherembodiment, the C:P ratio ranges from 1:0.001 to 0.01. In yet anotherembodiment, the C:P ratio ranges from 1:0.01 to 1:1. In yet anotherembodiment, the content of nitrogen exceeds the content of carbon.

XPS may also be used to detect individual bonds between elements. In thecase of a composite, the interface between the carbon and the siliconmay include an C—X bond, wherein X is the primary element that alloyswith lithium (such as C—Si bond for a silicon electrochemical modifier).The presence of C—X may affect the performance of the material. Thispercent of C—X bonds within a composite can be characterized using XPS.In one embodiment the percent of C—X bonds as measured by XPS is between0% and 50%. In another embodiment the percent of C—X bonds is between 0%and 10%, 0% and 5%, 0% and 3%, 0% and 2%, 0% and 1%, 1% and 2%, between10% and 50%, or greater than 50%. In yet another embodiment, the C—Xbond also produces a material in-situ that is also capable of alloyingelectrochemically with silicon.

The carbon material comprising the composite material can include bothsp3 and sp2 hybridized carbons. The percentage of sp2 hybridization canbe measured by XPS using the Auger spectrum, as known in the art. It isassumed that for materials which are less than 100% sp², the remainderof the bonds are sp³. The carbon materials range from about 1% sp²hybridization to 100% sp² hybridization. Other embodiments includecarbon materials comprising from about 25% to about 95% sp², from about50%-95% sp², from about 50% to about 75% sp², from about 65% to about95% sp² or about 65% sp².

In certain embodiments, XPS can be examined to determine the specificnature of specific bonding structures within the silicon comprising thecomposite. For example, XPS can be examined in the region in thevicinity of 100 eV to ascertain details of Si 2p bonding in the siliconstructure. In certain embodiments, the silicon material compriseselemental silicon exhibiting an XPS peak located at 99.4 eV. In certainembodiments, the silicon material comprises Si3N4 exhibiting an XPS peaklocated at 101.7 eV. In certain embodiments, the silicon comprisesorganic silicon exhibiting an XPS peak located at 102 eV. In certainembodiments, the silicon comprises organic silicon exhibiting an XPSpeak located at 103.5 eV.

The composite material may also incorporate an electrochemical modifierselected to optimize the electrochemical performance of the non-modifiedcomposite. The electrochemical modifier may be incorporated within thepore structure and/or on the surface of the porous carbon scaffold,within the embedded silicon, or within the final layer of carbon, orconductive polymer, coating, or incorporated in any number of otherways. For example, in some embodiments, the composite materials comprisea coating of the electrochemical modifier (e.g., silicon or Al₂O₃) onthe surface of the carbon materials. In some embodiments, the compositematerials comprise greater than about 100 ppm of an electrochemicalmodifier. In certain embodiments, the electrochemical modifier isselected from iron, tin, silicon, nickel, aluminum and manganese.

In certain embodiments the electrochemical modifier comprises an elementwith the ability to lithiate from 3 to 0 V versus lithium metal (e.g.silicon, tin, sulfur). In other embodiments, the electrochemicalmodifier comprises metal oxides with the ability to lithiate from 3 to 0V versus lithium metal (e.g. iron oxide, molybdenum oxide, titaniumoxide). In still other embodiments, the electrochemical modifiercomprises elements which do not lithiate from 3 to 0 V versus lithiummetal (e.g. aluminum, manganese, nickel, metal-phosphates). In yet otherembodiments, the electrochemical modifier comprises a non-metal element(e.g. fluorine, nitrogen, hydrogen). In still other embodiments, theelectrochemical modifier comprises any of the foregoing electrochemicalmodifiers or any combination thereof (e.g. tin-silicon, nickel-titaniumoxide).

The electrochemical modifier may be provided in any number of forms. Forexample, in some embodiments the electrochemical modifier comprises asalt. In other embodiments, the electrochemical modifier comprises oneor more elements in elemental form, for example elemental iron, tin,silicon, nickel or manganese. In other embodiments, the electrochemicalmodifier comprises one or more elements in oxidized form, for exampleiron oxides, tin oxides, silicon oxides, nickel oxides, aluminum oxidesor manganese oxides.

In other embodiments, the electrochemical modifier comprises iron. Inother embodiments, the electrochemical modifier comprises tin. In otherembodiments, the electrochemical modifier comprises silicon. In someother embodiments, the electrochemical modifier comprises nickel. In yetother embodiments, the electrochemical modifier comprises aluminum. Inyet other embodiments, the electrochemical modifier comprises manganese.In yet other embodiments, the electrochemical modifier comprises Al₂O₃.In yet other embodiments, the electrochemical modifier comprisestitanium. In yet other embodiments, the electrochemical modifiercomprises titanium oxide. In yet other embodiments, the electrochemicalmodifier comprises lithium. In yet other embodiments, theelectrochemical modifier comprises sulfur. In yet other embodiments, theelectrochemical modifier comprises phosphorous. In yet otherembodiments, the electrochemical modifier comprises molybdenum. In yetother embodiments, the electrochemical modifier comprises germanium. Inyet other embodiments, the electrochemical modifier comprises arsenic.In yet other embodiments, the electrochemical modifier comprisesgallium. In yet other embodiments, the electrochemical modifiercomprises phosphorous. In yet other embodiments, the electrochemicalmodifier comprises selenium. In yet other embodiments, theelectrochemical modifier comprises antimony. In yet other embodiments,the electrochemical modifier comprises bismuth. In yet otherembodiments, the electrochemical modifier comprises tellurium. In yetother embodiments, the electrochemical modifier comprises indium.

Accordingly, in some embodiments the composite material comprises morethan one carbon allotrope, including hard carbon and a second allotrope,selected from species including, but not limited to, graphite, amorphouscarbon (soft and hard), diamond, C60, carbon nanotubes (e.g., singleand/or multi-walled), graphene and carbon fibers. In some embodiments,the second carbon form is graphite. In other embodiments, the secondform is soft carbon. The ratio of carbon material (e.g., hard carbon) tosecond carbon allotrope can be tailored to fit any desiredelectrochemical application.

In certain embodiments, the mass ratio of hard carbon to second carbonallotrope in the composite materials ranges from about 0.01:1 to about100:1. In other embodiments, the mass ratio of hard carbon to secondcarbon allotrope ranges from about 1:1 to about 10:1 or about 5:1. Inother embodiments, the mass ratio of hard carbon to second carbonallotrope ranges from about 1:10 to about 10:1. In other embodiments,the mass ratio of hard carbon to second carbon allotrope ranges fromabout 1:5 to about 5:1. In other embodiments, the mass ratio of hardcarbon to second carbon allotrope ranges from about 1:3 to about 3:1. Inother embodiments, the mass ratio of hard carbon to second carbonallotrope ranges from about 1:2 to about 2:1.

Multiple carbon allotropes can be combined within a single composite tofurther improve electrochemical performance. For example, a hard carboncan be blended with both graphite and soft carbon to change the densityas well as the capacity or first cycle efficiency. The three or morecarbon allotropes will have a synergistic effect, creating a uniquestructure and performance. In certain embodiments, the mass ratio ofhard carbon to the sum of the masses for all other carbon allotropespresent in the composite material ranges from about 0.01:1 to about100:1. In other embodiments, the mass ratio of hard carbon to the sum ofthe masses for all other carbon allotropes in the composite materialranges from about 1:1 to about 10:1 or about 5:1. In other embodimentsthe mass ratio of hard carbon to the sum of the masses for all othercarbon allotropes in the composite material ranges from about 1:10 toabout 10:1. In other embodiments, the mass ratio of hard carbon to thesum of the masses for all other carbon allotropes in the compositematerial ranges from about 1:5 to about 5:1. In other embodiments, themass ratio of hard carbon to the sum of the masses for all other carbonallotropes in the composite material ranges from about 1:3 to about 3:1.In other embodiments, the mass ratio of hard carbon to the sum of themasses for all other carbon allotropes in the composite material rangesfrom about 1:2 to about 2:1.

The electrochemical properties of the composite material can bemodified, at least in part, by the amount of the electrochemicalmodifier in the material, wherein the electrochemical modifier is analloying material such as silicon, tin, indium, aluminum, germanium,gallium. Accordingly, in some embodiments, the composite materialcomprises at least 0.10%, at least 0.25%, at least 0.50%, at least 1.0%,at least 5.0%, at least 10%, at least 25%, at least 50%, at least 75%,at least 90%, at least 95%, at least 99% or at least 99.5% of theelectrochemical modifier. For example, in some embodiments, thecomposite materials comprise between 0.5% and 99.5% carbon and between0.5% and 99.5% electrochemical modifier. In a preferred embodiment, thecomposite material comprises 70%-99% silicon, for example between 75%and 95%, for example between 80% and 95%. The percent of theelectrochemical modifier is calculated on weight percent basis (wt %).In some other more specific embodiments, the electrochemical modifiercomprises iron, tin, silicon, nickel and manganese. In a preferredembodiment, the composite material comprises 70%-99% silicon, forexample between 75% and 95%, for example between 80% and 95%.

The unmodified carbon materials have purities not previously obtainedwith hard carbon materials. While not wishing to be bound by theory, itis believed that the high purity of the unmodified carbon materialscontributes to the superior electrochemical properties of the same. Insome embodiments, the unmodified carbon material comprises low totalTXRF impurities (excluding any intentionally included electrochemicalmodifier). Thus, in some embodiments the total TXRF impurity content(excluding any intentionally included electrochemical modifier) of allother TXRF elements in the carbon material (as measured by protoninduced x-ray emission) is less than 1000 ppm. In other embodiments, thetotal TXRF impurity content (excluding any intentionally includedelectrochemical modifier) of all other TXRF elements in the carbonmaterial is less than 800 ppm, less than 500 ppm, less than 300 ppm,less than 200 ppm, less than 150 ppm, less than 100 ppm, less than 50ppm, less than 25 ppm, less than 10 ppm, less than 5 ppm or less than 1ppm.

In addition to low content of undesired TXRF impurities, the disclosedunmodified carbon materials may comprise high total carbon content. Insome examples, in addition to carbon, the carbon material may alsocomprise oxygen, hydrogen, nitrogen and an optional electrochemicalmodifier. In some embodiments, the material comprises at least 75%carbon, 80% carbon, 85% carbon, at least 90% carbon, at least 95%carbon, at least 96% carbon, at least 97% carbon, at least 98% carbon orat least 99% carbon on a weight/weight basis. In some other embodiments,the carbon material comprises less than 10% oxygen, less than 5% oxygen,less than 3.0% oxygen, less than 2.5% oxygen, less than 1% oxygen orless than 0.5% oxygen on a weight/weight basis. In other embodiments,the carbon material comprises less than 10% hydrogen, less than 5%hydrogen, less than 2.5% hydrogen, less than 1% hydrogen, less than 0.5%hydrogen or less than 0.1% hydrogen on a weight/weight basis. In otherembodiments, the carbon material comprises less than 5% nitrogen, lessthan 2.5% nitrogen, less than 1% nitrogen, less than 0.5% nitrogen, lessthan 0.25% nitrogen or less than 0.01% nitrogen on a weight/weightbasis. The oxygen, hydrogen and nitrogen content of the disclosed carbonmaterials can be determined by combustion analysis. Techniques fordetermining elemental composition by combustion analysis are well knownin the art.

The total ash content of an unmodified carbon material may, in someinstances, have an effect on the electrochemical performance of a carbonmaterial. Accordingly, in some embodiments, the ash content (excludingany intentionally included electrochemical modifier) of the carbonmaterial ranges from 0.1% to 0.001% weight percent ash, for example insome specific embodiments the ash content (excluding any intentionallyincluded electrochemical modifier) of the carbon material is less than0.1%, less than 0.08%, less than 0.05%, less than 0.03%, than 0.025%,less than 0.01%, less than 0.0075%, less than 0.005% or less than0.001%.

In other embodiments, the composite material comprising a porous siliconmaterial comprises a total TXRF impurity content of all other elements(excluding any intentionally included electrochemical modifier) of lessthan 500 ppm and an ash content (excluding any intentionally includedelectrochemical modifier) of less than 0.08%. In further embodiments,the composite material comprises a total TXRF impurity content of allother elements (excluding any intentionally included electrochemicalmodifier) of less than 300 ppm and an ash content (excluding anyintentionally included electrochemical modifier) of less than 0.05%. Inother further embodiments, the composite material comprises a total TXRFimpurity content of all other elements (excluding any intentionallyincluded electrochemical modifier) of less than 200 ppm and an ashcontent (excluding any intentionally included electrochemical modifier)of less than 0.05%. In other further embodiments, the composite materialcomprises a total TXRF impurity content of all other elements (excludingany intentionally included electrochemical modifier) of less than 200ppm and an ash content (excluding any intentionally includedelectrochemical modifier) of less than 0.025%. In other furtherembodiments, the composite material comprises a total TXRF impuritycontent of all other elements (excluding any intentionally includedelectrochemical modifier) of less than 100 ppm and an ash content(excluding any intentionally included electrochemical modifier) of lessthan 0.02%. In other further embodiments, the composite materialcomprises a total TXRF impurity content of all other elements (excludingany intentionally included electrochemical modifier) of less than 50 ppmand an ash content (excluding any intentionally included electrochemicalmodifier) of less than 0.01%.

In other embodiments, the composite material comprising a porous siliconmaterial comprises a total TXRF impurity content of all other elements(excluding any intentionally included electrochemical modifier) ofgreater than 500 ppm and an ash content (excluding any intentionallyincluded electrochemical modifier) of greater than 0.08%. In furtherembodiments, the composite material comprises a total TXRF impuritycontent of all other elements (excluding any intentionally includedelectrochemical modifier) of greater than 5000 ppm and an ash content(excluding any intentionally included electrochemical modifier) ofgreater than 0.5%. In other further embodiments, the composite materialcomprises a total TXRF impurity content of all other elements (excludingany intentionally included electrochemical modifier) of greater than 1%and an ash content (excluding any intentionally included electrochemicalmodifier) of greater than 0.5%. In other further embodiments, thecomposite material comprises a total TXRF impurity content of all otherelements (excluding any intentionally included electrochemical modifier)of greater than 2% and an ash content (excluding any intentionallyincluded electrochemical modifier) of greater than 1%. In other furtherembodiments, the composite material comprises a total TXRF impuritycontent of all other elements (excluding any intentionally includedelectrochemical modifier) of greater than 3% and an ash content(excluding any intentionally included electrochemical modifier) ofgreater than 2%. In other further embodiments, the composite materialcomprises a total TXRF impurity content of all other elements (excludingany intentionally included electrochemical modifier) of greater than 4%and an ash content (excluding any intentionally included electrochemicalmodifier) of greater than 3%. In other further embodiments, thecomposite material comprises a total TXRF impurity content of all otherelements (excluding any intentionally included electrochemical modifier)of greater than 5% and an ash content (excluding any intentionallyincluded electrochemical modifier) of greater than 4%. In other furtherembodiments, the composite material comprises a total TXRF impuritycontent of all other elements (excluding any intentionally includedelectrochemical modifier) of greater than 6% and an ash content(excluding any intentionally included electrochemical modifier) ofgreater than 5%. In other further embodiments, the composite materialcomprises a total TXRF impurity content of all other elements (excludingany intentionally included electrochemical modifier) of greater than 7%and an ash content (excluding any intentionally included electrochemicalmodifier) of greater than 6%. In other further embodiments, thecomposite material comprises a total TXRF impurity content of all otherelements (excluding any intentionally included electrochemical modifier)of greater than 8% and an ash content (excluding any intentionallyincluded electrochemical modifier) of greater than 7%. In other furtherembodiments, the composite material comprises a total TXRF impuritycontent of all other elements (excluding any intentionally includedelectrochemical modifier) of greater than 9% and an ash content(excluding any intentionally included electrochemical modifier) ofgreater than 8%. In other further embodiments, the composite materialcomprises a total TXRF impurity content of all other elements (excludingany intentionally included electrochemical modifier) of greater than 10%and an ash content (excluding any intentionally included electrochemicalmodifier) of greater than 9%.

The amount of individual TXRF impurities present in the disclosedcomposite material comprising a porous silicon material can bedetermined by proton induced x-ray emission. Individual TXRF impuritiesmay contribute in different ways to the overall electrochemicalperformance of the disclosed composite materials. Thus, in someembodiments, the level of sodium present in the composite material isless than 1000 ppm, less than 500 ppm, less than 100 ppm, less than 50ppm, less than 10 ppm, or less than 1 ppm. In some embodiments, thelevel of magnesium present in the composite material is less than 1000ppm, less than 100 ppm, less than 50 ppm, less than 10 ppm, or less than1 ppm. In some embodiments, the level of aluminum present in thecomposite material is less than 1000 ppm, less than 100 ppm, less than50 ppm, less than 10 ppm, or less than 1 ppm. In some embodiments, thelevel of silicon present in the composite material is less than 500 ppm,less than 300 ppm, less than 100 ppm, less than 50 ppm, less than 20ppm, less than 10 ppm or less than 1 ppm. In some embodiments, the levelof phosphorous present in the composite material is less than 1000 ppm,less than 100 ppm, less than 50 ppm, less than 10 ppm, or less than 1ppm. In some embodiments, the level of sulfur present in the compositematerial is less than 1000 ppm, less than 100 ppm, less than 50 ppm,less than 30 ppm, less than 10 ppm, less than 5 ppm or less than 1 ppm.In some embodiments, the level of chlorine present in the compositematerial is less than 1000 ppm, less than 100 ppm, less than 50 ppm,less than 10 ppm, or less than 1 ppm. In some embodiments, the level ofpotassium present in the composite material is less than 1000 ppm, lessthan 100 ppm, less than 50 ppm, less than 10 ppm, or less than 1 ppm. Inother embodiments, the level of calcium present in the compositematerial is less than 100 ppm, less than 50 ppm, less than 20 ppm, lessthan 10 ppm, less than 5 ppm or less than 1 ppm. In some embodiments,the level of chromium present in the composite material is less than1000 ppm, less than 100 ppm, less than 50 ppm, less than 10 ppm, lessthan 5 ppm, less than 4 ppm, less than 3 ppm, less than 2 ppm or lessthan 1 ppm. In other embodiments, the level of iron present in thecomposite material is less than 50 ppm, less than 20 ppm, less than 10ppm, less than 5 ppm, less than 4 ppm, less than 3 ppm, less than 2 ppmor less than 1 ppm. In other embodiments, the level of nickel present inthe composite material is less than 20 ppm, less than 10 ppm, less than5 ppm, less than 4 ppm, less than 3 ppm, less than 2 ppm or less than 1ppm. In some other embodiments, the level of copper present in thecomposite material is less than 140 ppm, less than 100 ppm, less than 40ppm, less than 20 ppm, less than 10 ppm, less than 5 ppm, less than 4ppm, less than 3 ppm, less than 2 ppm or less than 1 ppm. In yet otherembodiments, the level of zinc present in the composite material is lessthan 20 ppm, less than 10 ppm, less than 5 ppm, less than 2 ppm or lessthan 1 ppm. In yet other embodiments, the sum of all other TXRFimpurities (excluding any intentionally included electrochemicalmodifier) present in the composite material is less than 1000 ppm, lessthan 500 pm, less than 300 ppm, less than 200 ppm, less than 100 ppm,less than 50 ppm, less than 25 ppm, less than 10 ppm or less than 1 ppm.As noted above, in some embodiments other impurities such as hydrogen,oxygen and/or nitrogen may be present in levels ranging from less than10% to less than 0.01%.

In some embodiments, the unmodified composite material comprising aporous silicon material comprises undesired TXRF impurities near orbelow the detection limit of the proton induced x-ray emission analysis.For example, in some embodiments the unmodified composite materialcomprises less than 50 ppm sodium, less than 15 ppm magnesium, less than10 ppm aluminum, less than 8 ppm silicon, less than 4 ppm phosphorous,less than 3 ppm sulfur, less than 3 ppm chlorine, less than 2 ppmpotassium, less than 3 ppm calcium, less than 2 ppm scandium, less than1 ppm titanium, less than 1 ppm vanadium, less than 0.5 ppm chromium,less than 0.5 ppm manganese, less than 0.5 ppm iron, less than 0.25 ppmcobalt, less than 0.25 ppm nickel, less than 0.25 ppm copper, less than0.5 ppm zinc, less than 0.5 ppm gallium, less than 0.5 ppm germanium,less than 0.5 ppm arsenic, less than 0.5 ppm selenium, less than 1 ppmbromine, less than 1 ppm rubidium, less than 1.5 ppm strontium, lessthan 2 ppm yttrium, less than 3 ppm zirconium, less than 2 ppm niobium,less than 4 ppm molybdenum, less than 4 ppm, technetium, less than 7 ppmrubidium, less than 6 ppm rhodium, less than 6 ppm palladium, less than9 ppm silver, less than 6 ppm cadmium, less than 6 ppm indium, less than5 ppm tin, less than 6 ppm antimony, less than 6 ppm tellurium, lessthan 5 ppm iodine, less than 4 ppm cesium, less than 4 ppm barium, lessthan 3 ppm lanthanum, less than 3 ppm cerium, less than 2 ppmpraseodymium, less than 2 ppm, neodymium, less than 1.5 ppm promethium,less than 1 ppm samarium, less than 1 ppm europium, less than 1 ppmgadolinium, less than 1 ppm terbium, less than 1 ppm dysprosium, lessthan 1 ppm holmium, less than 1 ppm erbium, less than 1 ppm thulium,less than 1 ppm ytterbium, less than 1 ppm lutetium, less than 1 ppmhafnium, less than 1 ppm tantalum, less than 1 ppm tungsten, less than1.5 ppm rhenium, less than 1 ppm osmium, less than 1 ppm iridium, lessthan 1 ppm platinum, less than 1 ppm silver, less than 1 ppm mercury,less than 1 ppm thallium, less than 1 ppm lead, less than 1.5 ppmbismuth, less than 2 ppm thorium, or less than 4 ppm uranium.

In some embodiments, the unmodified composite material comprising aporous silicon material comprises undesired TXRF impurities near orbelow the detection limit of the proton induced x-ray emission analysis.In some specific embodiments, the unmodified composite materialcomprises less than 100 ppm sodium, less than 300 ppm silicon, less than50 ppm sulfur, less than 100 ppm calcium, less than 20 ppm iron, lessthan 10 ppm nickel, less than 140 ppm copper, less than 5 ppm chromiumand less than 5 ppm zinc as measured by TXRF. In other specificembodiments, the composite material comprises less than 50 ppm sodium,less than 30 ppm sulfur, less than 100 ppm silicon, less than 50 ppmcalcium, less than 10 ppm iron, less than 5 ppm nickel, less than 20 ppmcopper, less than 2 ppm chromium and less than 2 ppm zinc.

In other specific embodiments, the unmodified composite materialcomprising a porous silicon material comprises less than 50 ppm sodium,less than 50 ppm silicon, less than 30 ppm sulfur, less than 10 ppmcalcium, less than 2 ppm iron, less than 1 ppm nickel, less than 1 ppmcopper, less than 1 ppm chromium and less than 1 ppm zinc. In some otherspecific embodiments, the unmodified composite material comprising aporous silicon material comprises less than 100 ppm sodium, less than 50ppm magnesium, less than 50 ppm aluminum, less than 10 ppm sulfur, lessthan 10 ppm chlorine, less than 10 ppm potassium, less than 1 ppmchromium and less than 1 ppm manganese.

In certain embodiments, the composite material comprising a poroussilicon material comprises carbon and two or more differentelectrochemical modifiers. In embodiments, the composite materialcomprises silicon and one or more of the following species (orcombinations thereof): phosphorus, nitrogen, sulfur, boron or aluminum.In certain embodiments, the composite material comprises carbon, siliconand 1-20% of a Group 13 element or combination thereof. In other certainembodiments, the composite material comprises carbon, silicon and 1-20%of a Group 15 element, or combination thereof. In other certainembodiments, the composite material comprises carbon, silicon and 1-20%of lithium, sodium, or potassium, or combinations thereof. In othercertain embodiments, the composite material comprises carbon, siliconand 1-20% of lithium, sodium, or potassium, or combinations thereof.

The particle size of the composite material may expand upon lithiationas compared to the non-lithiated state. For example, the expansionfactor, defined as ratio of the average particle size of particles ofcomposite material comprising a porous silicon material upon lithiationdivided by the average particle size under non-lithiated conditions. Asdescribed in the art, this expansion factor can be relative large forpreviously known, non-optimal silicon-containing materials, for exampleabout 4 (corresponding to a 400% volume expansion upon lithiation). Thecurrent inventors have discovered composite materials comprising aporous silicon material that can exhibit a lower extent of expansion,for example, the expansion factor can vary from 3.5 to 4, from 3.0 to3.5, from 2.5 to 3.0, from 2.0 to 2.5, from 1.5 to 2.0, from 1.0 to 1.5.

It is envisioned that composite materials in certain embodiments willcomprise a fraction of trapped pore volume, namely, void volumenon-accessible to nitrogen gas as probed by nitrogen gas sorptionmeasurement. Without being bound by theory, this trapped pore volume isimportant in that it provides volume into which silicon can expand uponlithiation.

Accordingly, the composite materials comprises herein may comprise aratio of trapped pore volume to measured pore volume (as determined bynitrogen gas sorption) between 0.01:1 to 100:1. In certain embodiments,the composite materials comprise a ratio of trapped pore volume tomeasured pore volume between 0.01:1 and 0.05:1. In certain embodiments,the composite materials comprise a ratio of trapped pore volume tomeasured pore volume between 0.05:1 and 0.1:1. In certain embodiments,the composite materials comprise a ratio of trapped pore volume tomeasured pore volume between 0.1:1 and 0.2:1. In certain embodiments,the composite materials comprise a ratio of trapped pore volume tomeasured pore volume between 0.2:1 and 0.5:1. In certain embodiments,the composite materials comprise a ratio of trapped pore volume tomeasured pore volume between 0.5:1 and 1:1. In certain embodiments, thecomposite materials comprise a ratio of trapped pore volume to measuredpore volume between 1:1 and 2:1. In certain embodiments, the compositematerials comprise a ratio of trapped pore volume to measured porevolume between 2:1 and 5:1. In certain embodiments, the compositematerials comprise a ratio of trapped pore volume to measured porevolume between 5:1 and 10:1. In certain embodiments, the compositematerials comprise a ratio of trapped pore volume to measured porevolume between 10:1 and 20:1. In certain embodiments, the compositematerials comprise a ratio of trapped pore volume to measured porevolume between 20:1 and 50:1. In certain embodiments, the compositematerials comprise a ratio of trapped pore volume to measured porevolume between 50:1 and 100:1.

In certain preferred embodiments, the ratio of trapped void volume tothe silicon volume comprising the composite particle is between 0.1:1and 10:1. For example, the ratio of trapped void volume to the siliconvolume comprising the composite particle is between 1:1 and 5:1, or 5:1to 10:1. In preferred embodiments, the ratio of ratio trapped voidvolume to the silicon volume comprising the composite particle isbetween 2:1 and 5:1, or about 3:1, in order to efficiently accommodatethe maximum extent of expansion of silicon upon lithiation.

EXAMPLES Example 1 Performance Model of Novel Composite Materials

A full cell model was developed to simulate the approximate size andenergy of an 18650-type cell. LCO was chosen as the default cathode. Themodel accounts for material properties (density, packing, volumeexpansion), electrochemical performance characteristics (operatingvoltage, capacity, irreversible capacity), and cell level changes(required electrolyte, void volume). Table 2 compares the cell levelproperties from a commercially available cell and the output from themodel. Similar values are calculated using the model, providingconfidence in the model's ability to represent system level changes.

TABLE 2 Validation of performance model for a commercial cell. StandardCommercial Component Cell Model Prediction Cell type Stacked Pouch CellStacked Pouch Cell Anode Unknown Graphite Cathode Unknown LCO Cellcapacity 3.28 Ah 3.55 Ah (calculated) Operating Voltage 3.7 V 3.7 V(calculated) Cell energy 199 Wh/kg 174 Wh/kg 435 Wh/L (calculated) 437Wh/L (calculated)

Next, the values in Table 3 demonstrate cell level performance changeswhen the anode is modified to include the novel composite materialsdisclosed herein. At a cell level, there is a considerable increase(˜43%) in volumetric energy density, though limited change in Wh/kg inpart due to additional SEI losses. Without being bound by theory,prelithiation increase the gravimetric energy density further.

TABLE 3 Performance model applied to novel composite materials. StandardCommercial Novel Composite: Novel composite: Component Cell 650 mAh/ganode 1200 mAh/g anode Anode Graphite 30% Si—C + graphite >70% Si—C +graphite Cathode LCO LCO LCO Cell capacity 3.55 Ah 4.20 Ah 5.08 AhOperating 3.7 V 3.6 V 3.6 V Voltage Cell energy 174 Wh/kg 189 Wh/kg 215Wh/kg 437 Wh/L 510 Wh/L 619 Wh/L

Example 2 Examples of Porous Carbon Scaffold Materials

The variety of various porous carbon scaffold materials were obtainedfor study. A listing of the physicochemical attributes of the carbon islisted in Table 4. Carbon 1 was a commercial carbon; in addition to thecharacteristics reported in Table 2, the Dv,100 was 11.62 microns, theDv,10 was 0.6 micron, tap density was 0.27 g/cm³, the pH was 5.3, theash content was 0.016%, and the sum all impurities detected by PIXE wasas follows: silicon=48.680 ppm, calcium=12.910 ppm, iron=22.830 ppm,nickel=3.604 ppm, chromium=5.521.

Carbon 2 was a commercial carbon; in addition to the characteristicsreported in Table 1, the Dv,100 was 18.662 microns, the Dv,10 was 1.2micron, the span for particle size was 1.194, the uniformity forparticle size distribution was 0.367, the tap density was 0.2347 g/cm³,the pH was 6.709, the ash content was 0.005%, and the sum all impuritiesdetected by PIXE was as follows: calcium=20.5 ppm, iron=4.14 ppm,zinc=2.24 ppm, titanium=6.7 ppm.

Carbon 3 was a commercial carbon; in addition to the characteristicsreported in Table 1, the Dv,100 was 21.2 microns, the Dv,10 was 3.8micron, the span for particle size was 1.261, the uniformity forparticle size distribution was 0.387, the tap density was 0.52/cm³, thepH was 9.418, the ash content was 0.075%, and the sum all impuritiesdetected by PIXE was as follows: silicon=29.012 ppm, iron=3.183 ppm,zinc=0.555, potassium=6.952 ppm.

Carbon 4 was produced as follows from a resorcinol formaldehyde resin.First, 388 g of de-ionized water was mixed with 26 mL of glacial aceticacid, and 156 g of resorcinol in a 1 L beaker. The solution was mixed ona stir plate until all of the resorcinol is dissolved. The solution iscontinuously mixed and 2.2 g of ammonium acetate was added and allowedto dissolve. Next, 212 mL of formaldehyde solution (37 wt % formaldehydein water) was added to the stirring solution. The solution was allowedto stir for 5-10 minutes. The final solution was then poured into 1 Lpolypropylene bottles and placed at 85° C. for 24 hours. The resultingcured and solid resin was then freeze dried to remove all excess water,acid and formaldehyde to create a cryogel, which was then pyrolyzedaccording to methods described herein.

Carbon 5 and Carbon 6 were commercial carbons.

Carbon 7 was a commercial carbon; in addition to the characteristicsreported in Table 1, the Dv,100 was 35.2 microns, the Dv,10 was 2.69micron, the span for particle size was 1.765, the uniformity forparticle size distribution was 0.539, the tap density was 1.015-1.020g/cm³, and the pH was 3.099.

Carbon 8 was a commercial carbon.

Carbon 9 was produced as follows from a Urea Citric Acid resin. First400 g of pre-dried urea was mixed with 200 g of pre-dried citric acid.The mixture was then ground together into a very fine powder. The powdermixture was poured into a curing vessel and placed at 140° C. for 24hours. The resulting cured and solid resin, was then pyrolyzed accordingto methods described herein.

Carbon 10 was a commercial carbon; in addition to the characteristicsreported in Table 1, the Dv,100 was 18.6 microns, the Dv,10 was 2.48micron, the span for particle size was 1.348, the uniformity forparticle size distribution was 0.406, the tap density was 0.32 g/cm³,and the pH was 7.616.

Carbon 11 was graphite.

Carbons 12 was a commercial carbon. Carbon 13 was commercial carbon 1that was subsequently heated to 1100° C. for 1 hour under 5 mol % H2 gasin argon.

Carbon 14 was a hard carbon produced in a solvent-free process employinga polyol and an organic acid according to the procedures describedherein.

Carbon 15 was a hard carbon produced employing an epoxy compound andphosphoric acid according to the procedures described herein.

TABLE 4 Various characteristics of carbon according to Example 2. PoreDistribution % micropores, PV Dv, 50 % mesopores, Carbon SSA (m2/g)(cm³/g) (micron) % macropores 1 726 0.835 3.78 28, 70, 2 2 1707 1.2837.727 46, 54, 0 3 1744 0.72 7.22 94, 4, 1 4 677-749 1.097-1.14 <38 um11, 80, 9 5 Aggregates Difficult to ascertain of nm sized due toagglomerates particles 6 1635 1.35 <38 um 25, 74, 0 7 10.03 0.00085 8.760, 0, 100 8 186 0.089 <38 um 86, 10, 3 9 39 0.044 <38 um 11, 40, 49 101678 1.22 6.31 47, 53, 0 11 1.3 0.003 14.7 N/A 12 697 0.67 5.3 34, 66, 013 679 0.544 3.8 48, 52, 0 14 39 0.044 N/A 11, 39, 50 15 14 0.010 11.341, 30, 29

Example 3 Production of Various Composite Materials Via SiliconDeposition on Porous Silicon Scaffold

A variety of different composite materials were produced according tocurrent disclosure, in this example, the silicon was embedded within aporous carbon scaffold via a chemical vapor deposition techniqueemploying silane gas, as generally described herein. For this specificexample, samples were processed in a tube furnace with 2 mol % silanegas flow mixed with nitrogen gas, and held for various times andtemperatures as noted. A summary of sample processing is presented inTable 5. The final loading of silicon in the silicon carbon compositecan be determined as known in the art, for example from the weight lossobserved employing thermal gravimetric analysis (TGA), a technique knownin the art.

TABLE 5 Summary of composite samples produced according to Example 3.Composite Porous Set Temp. Flow rate Pressure Silane dwell Total wt wt %silicon Sample # Carbon (° C.) (sccm) (Torr) time (min) % gain in Si—C 11 550 ~50 760 30 0.7  1% 2 2 550 ~50 760 30 6  6% 3 1 550 550 550 60 8 7% 4 2 550 ~100 760 60 29 22% 5 1 550 ~100 760 90 11 10% 6 2 550 ~100760 90 46 32% 7 5 550 ~100 760 60 33 25% 8 4 550 ~100 760 90 44 31% 9 2550 ~100 760 90 154 N/A 10 4 550 ~100 760 90 279 N/A 11 2 500 ~100 76090 64 N/A 12 4 500 ~100 760 90 101 N/A 13 4 550 ~200 760 120 190 N/A 144 550 ~200 760 120 162 62% 15 4 500 ~200 760 120 127 56% 16 1 500 ~200760 120 33 25% 17 4 550 ~200 760 120 134 57% 18 1 550 ~200 760 120 3526% 19 4 450 ~200 760 120 −3  0% 20 1 450 ~200 760 120 −2  0% 21 4 480~200 760 120 56 36% 22 1 480 ~200 760 120 11 10% 23 4 500 ~200 760 12063 38% 24 6 500 ~200 760 120 52 34% 25 7 500 ~200 760 120 2  2% 26 8 500~200 760 120 3  3% 27 6 500 ~200 760 120 54 35% 28 8 500 ~200 760 120 8 7% 29 7 500 ~200 760 120 2  2% 30 9 500 ~200 760 120 34 25% 31 3 500~200 760 120 26 21% 32 10 500 ~200 760 120 116 54% 33 9 500 ~200 760 15057 36% 34 3 500 ~200 760 150 81 45% 35 4 500 ~200 760 90 98 49% 36 10500 ~200 760 90 41 29% 37 6 500 ~200 760 150 113 53% 38 8 500 ~200 760150 4  4% 39 4 500 ~200 760 120 116 51% 40 10 500 ~200 760 120 58 23% 419 500 ~200 760 188 72 42% 42 7 500 ~200 760 188 7  7% 43 4 500 300 760110 154 59% 44 10 500 300 760 110 173 38% 45 10 500 300 760 120 122 55%46 10 500 300 760 120 134 57% 47 10 500 300 760 120 130 57% 48 10 500300 760 90 92 48% 49 10 500 300 760 60 57 36% 50 10 480 300 760 120 10952% 51 10 470 300 760 120 5  5% 52 10 475 300 760 120 92 48% 53 10 520300 760 90 94 48% 54 10 475 300 760 120 85 46% 55 11 475 300 760 90 1.5 1% 56 10 475 300 760 120 118 54% 57 10 475 300 760 120 92 48% 58 10 475300 760 120 118 54% 59 10 475 300 760 120 134 57% 60 4 475 380 760 90 9549% 61 12 475 380 760 90 81 45%

Example 4 Production of Various Composite Materials Via SiliconDeposition on Porous Silicon Scaffold Followed by Chemical VaporDeposition to Create a Carbon Layer Surrounding the Particle

Certain samples from the previous example were further processed tocreate a surface carbon layer via chemical vapor deposition, alsoaccomplished in a tube furnace, employing propane gas at elevatedtemperature for a certain period of time, as noted. The preparation dataare summarized in Table 6.

TABLE 6 Summary of composite samples produced according to Example 4.Sample Propane Set Temp. (° C.) Time (min.). 9 850 30 10 850 30 11 80015 12 800 15 13 800 10 14 800 15 39 750 30 40 750 30 41 750 30 42 750 3043 750 10 44 750 10 57 750 30 58 800 30 59 800 30

Example 5 Physicochemical Properties of Various Composite Materials

The surface area, pore volume, and pore volume distribution of varioussamples according to the above examples were determined by nitrogensorption as described within this disclosure. Table 7 summarizes thedata.

TABLE 7 Physicochemical properties of various composite samples. Porevolume distribution % Composite micropores, % mesopore, % Sample SSA(m2/g) PV (cm³/g) macropores 1 623 0.495 42, 58, 0 2 1359 1.02 45, 55, 03 516 0.44 38, 62, 0 4 1158 0.86 45, 55, 0 5 423 0.386 34, 66, 1 6 9100.665 46, 54, 0 7 73 0.12  5, 49, 45 8 342 0.66  6, 83, 11 9 10 0.01611, 82, 7 10 27 0.065  3, 88, 9 11 193 0.362  8, 92, 0 12 187 0.42  4,91, 6 13 80 0.199  3, 89, 8 14 95 0.229  4, 84, 13 15 150 0.28  7, 86, 716 291 0.208 50, 49, 1 17 117 0.201  9, 81, 10 18 282 0.204 49, 50, 1 19576 1.06  8, 83, 10 20 592 0.493 29, 60, 0 21 296 0.547  8, 80, 13 22475 0.371 42, 57, 1 23 285 0.512  8, 81, 11 24 222 0.233 28, 72, 0 25N/A N/A N/A 26 N/A N/A N/A 27 211 0.249 22, 78, 0 28 1.5 0.003 11, 0, 8929 N/A N/A N/A 30 4.7 0.0068  5, 42, 53 31 980 0.417 94, 4, 2 32 3090.243 42, 58, 0 33 1.9 0.0014  2, 32, 65 34 191 0.085 90, 7, 3 35 2500.44  8, 75, 17 36 927 0.719 43, 57, 0 37 2.4 0.0017  6, 34, 60 38 0.280.001  0, 43, 57 39 127 0.315  4, 81, 15 40 399 0.433 25, 75, 0 41 2.50.0035  1, 53, 46 42 0.36 0.0007  3, 0, 97 43 106 0.25  3, 87, 10 44 5620.471 39, 61, 0 45 314 0.254 41, 59, 0 46 254 0.211 39, 61, 0 47 2820.231 40, 60, 0 48 507 0.416 40, 60, 0 49 688 0.55 41, 59, 0 50 3570.311 36, 64, 0 51 N/A N/A N/A 52 406 0.36 35, 65, 0 53 443 0.35 42, 58,0 54 474 0.404 37, 63, 0 55 2 0.002  8, 45, 43 56 240 0.214 35, 65, 0 57182 0.226 19, 81, 0 58 15 0.026  6, 90, 5 59 12 0.02  8, 86, 6 60 2830.43  7, 66, 27 61 75 0.056 47, 50, 3

Example 6 Electrochemical Properties of Various Composite Materials

A variety of composites were produced according to the above examples.Said samples were studied for their electrochemical properties. In Table8 presents the data for the material tested an as anode in a half cell,wherein said anode comprises active material, binder, and conductivecarbon comprised 60%, 20%, and 20% of the electrode mass respectively.These samples were assembled into half-cells, and tested for five cyclesat a rate of C/10, and further cycles at C/5. The electrochemicaltesting data are summarized in Table 8. Unless otherwise stated, theaverage Coulombic efficiency and capacity retention are reported overcycle 7 to cycle 25, capacity is reported for cycle 6.

TABLE 8 Electrochemical characterization of various composite samples.Composite First cycle Avg. Coulombic Sample efficiency Capacityefficiency (%) 1 N/A N/A N/A 2 N/A N/A N/A 3 N/A N/A N/A 4 24%  468098.73  5 N/A N/A N/A 6 25%  554 099.26  7 N/A N/A N/A 8 27%  554096.53  (cycles 7-10) 9 40%  144 099.38  10 46%  334 N/A 11 24%  239099.30  12 41%  795 098.54  13 69% 1772 099.00  14 60% 1268 099.42  1570% 1895 098.54  (cycles 7-15) 16 33%  440 N/A 17 74% 2026 098.34  1857%  854 099.35  (cycles 7-20) 19 N/A N/A N/A 20 N/A N/A N/A 21 42 106997.91 (Cycles 7-20) 22 26  358 97.94 23 N/A N/A N/A 24 N/A N/A N/A 25N/A N/A N/A 26 N/A N/A N/A 27 49  755 99.45 28 N/A N/A N/A 29 N/A N/AN/A 30 62  779 99.16 31 26  261 96.66 32 63 1487 98.98 33 76 1331 92.8934 67 1123 99.11 35 58 1453 97.53 (cycles 7-20) 36 23  429 97.49 (cycles7-10) 37 82 2082 91.95 38 N/A N/A N/A 39 66 1754 98.78 40 30  441 N/A 4178 1489 96.22 42 N/A N/A N/A 43 68 2028 98.02 44 48  920 99.34 45 691410 98.6  46 73 1856 97.85 47 73 1631 98.16 48 63 1514 99.05 49 40  754N/A 50 67 1519 99.16 51 N/A N/A N/A 52 54 1042 99.52 53 59 1178 98.78 5451  974 99.34 55 N/A N/A N/A 56 68 1593 99.42 57 50  756 99.53 58 681177 99.26 59 67 1099 99.36 60 N/A N/A N/A 61 73 1650 99.31 N/A refersthat the information is either not available or pending.

Example 7 Electrochemical Characterization of Various CompositeMaterials in Blends with Graphite

A variety of composites were produced according to the above examples. Aselected number of said samples were studied for their electrochemicalproperties. Table 9 presents the data for the material tested as ananode in a half cell, wherein said anode comprises active material,binder, and conductive carbon comprised 80%, 10%, and 10% of theelectrode mass respectively. The active material was further comprisedgraphite, with the % of graphite and % of sample adjusted in order toachieve an approximate capacity in the range of 500-800 mAh/g. Forsample 13, the electrode comprised 24% of sample 13 and 76% graphite.For sample 14, the electrode comprised 30% of sample 14 and 70%graphite. For sample 15, the electrode comprised 19% of sample 15 and81% graphite. For sample 32, the electrode comprised 24% of sample 32and 76% graphite. For sample 33, the electrode comprised 27% of sample33 and 73% graphite. For sample 35, the electrode comprised 24% ofsample 35 and 76% graphite. For sample 50, the electrode comprised 25%of sample 35 and 75% graphite. These samples were assembled intohalf-cells, and tested for five cycles at a rate of C/10, and furthercycles at C/5. The electrochemical testing data are summarized in Table8. Unless otherwise stated, the average Coulombic efficiency andcapacity retention are reported over cycle 7 to cycle 25, capacity isreported for cycle 6.

TABLE 9 Electrochemical characterization of various composite samples ingraphite blends. Composite First cycle Avg. Coulombic Sample efficiencyCapacity efficiency (%) 13 76% 647 99.19 14 69% 596 99.61 15 78% 62699.13 (cycles 7 to 20) 32 79% 515 N/A 33 73% 595 N/A 35 65% 538 N/A 5072 603 99.77

Example 8 Filling of Pores of Microporous Carbon Materials Via SiliconDeposition

Microporous carbon (Carbon 3) was examined for its pore volumedistribution before and after either 120 min (Sample 31) or 150 min(Sample 34) treatment with silane to create composite materialscomprising silicon and carbon. The pore volume distributions of thesesamples are depicted in FIG. 2. As can be seen, there was a substantialdecrease in the pore volume in the micropore range, consistent withfilling of the micropores within the carbon scaffold with silicon.

Example 9 Filling of Pores of Mixed Micro-, Meso, and Macroporous CarbonMaterials Via Silicon Deposition

A carbon with mixed micro-, meso-, and macroporous nature (Carbon 2) wasexamined for its pore volume distribution before and after either 60 min(Sample 11) or 90 min treatment (Sample 9) with silane to createcomposite materials comprising silicon and carbon. The pore volumedistributions of these samples are depicted in FIG. 3. As can be seen,there was a substantial decrease in the pore volume in the microporerange, mesopore range, and macropore range, consistent with filling ofthe micropores, mesopores, and macropores within the carbon scaffoldwith silicon.

Example 10 Filling of Pores of Macroporous Carbon Materials Via SiliconDeposition

A carbon with macroporous nature (Carbon 4) was examined for its porevolume distribution before and after either 90 min treatment with silane(Sample 8), or after 90 min treatment with silane and an additional 30min treatment with propane (Sample 10), or after 120 min treatment withsilane and an additional 10 min treatment with propane (Sample 13) tocreate composite materials comprising silicon and carbon. The porevolume distributions of these samples are depicted in FIG. 4. As can beseen, there was a substantial decrease in the pore volume in themacropore range, consistent with filling of the macropores within thecarbon scaffold with silicon. Additionally, with the subsequent propanetreatment (layering of additional carbon on the particle surface), therewas additional loss in macropore volume, without being bound by theory,this observation is consistent with the CVD carbon coating providing forcapping off of macropores with reduction in macropore volume.

Accordingly, it is envisioned that composite materials in certainembodiments will comprise a fraction of trapped pore volume, namely,void volume non-accessible to nitrogen gas as probed by nitrogen gassorption measurement. Without being bound by theory, this trapped porevolume is important in that it provides volume into which silicon canexpand upon lithiation.

Example 11 Capping Off of Pores within the Porous Carbon Scaffold ViaCVD

Carbon coating porous materials by thermal chemical vapor depositionwill cap micropores rather than fill pores with carbon. This is bestobserved by carbon CVD on a purely microporous carbon (Carbon 3). Asseen in the table below, the material's specific surface area drops from1720 m²/g down to 6 m²/g. The pore volume also decreases to a negligiblevalue. The evidence for capping is seen in the nitrogen pycnometry data,the pellet density and the acetone pycnometry. Pellet was measured bycompressing powder in a die at a pressure of 2000 kg/cm2. Acetonepycnometry was measured by submerging the powder in acetone andmeasuring liquid displacement. The starting apparent skeletal density is2.24 g/cc for a pure microporous carbon. After CVD of carbon on thematerial, the apparent skeletal density drops to 1.49 g/cc, suggestingvoid space creation in the material. The data are summarized in Table 10and shown graphically in the pore volume distributions in FIG. 5.

TABLE 10 Example of capping micropore in carbon scaffold particle.Material Carbon 3, Carbon 3, Metric Non-treated CVD coated BET PoreVolume (cc/g) 0.739 0.010 BET Specific Surface Area (m2/g) 1720 6 N2Pycnometry Density 2.24 1.49 Acetone Pycnometry 2.17 1.45 Pellet Density(2000 kg/cm2) 0.67 0.91

Example 12 Electrochemical Characterization of Composite Material inFull Cell Coin Cell

The electrochemical performance of composite samples were examined forthe material as an anode comprising 80% active material, 10% conductivecarbon, and 10% binder, wherein the active further comprises 30% of thesample to be tested and 70% graphite. Alternatively, the electrochemicalperformance of composite samples was examined for an anode comprising80% active material, 10% conductive carbon, and 10% binder.Alternatively, the electrochemical performance of composite samples wasexamined for an anode comprising 90% active material, 5% conductivecarbon, and 5% binder. Alternatively, the electrochemical performance ofcomposite samples was examined for an anode comprising 90% activematerial, 2% conductive carbon, and 8% binder. Alternatively, theelectrochemical performance of composite samples was examined for ananode comprising 93% active material, 2% conductive carbon, and 5%binder. The active material in this context comprised the sample to betested, for example the silicon carbon composite and graphite, whereinthe active material comprised 10-60% of the silicon carbon composite and40-90% graphite.

Full cell coin cell were constructed as follows. The anode and cathodewere paired by collecting the half cell absolute 5^(th) cycle insertion(anode) and first cycle extraction (cathode) capacities, and matchingelectrodes such that a 5-15% excess anode ratio was satisfied. Coincells were constructed using LiNiCoAlO anode. After fabrication, thecells were electrochemically formed with 5 charge/discharge sequencesfrom 2.0-4.2 V. The first two sequences were performed at C/10 currentwith a C/20 hold at 4.2 V, and the following three sequences wereperformed at C/5, again with a C/20 hold. For evaluation of cyclestability, the cells were cycled from 2.0-4.2 V at C/2 with a C/20 hold.

Alternatively, cells were electrochemically formed with 2charge/discharge sequences from 2.5-4.2V, wherein the first sequence wasperformed at C/10 current with a C/20 hold at 4.2V. Subsequent sequenceswere performed at C/5, with a C/10 hold. For evaluation of cyclestability, the cells were cycled from 2.5-4.2V at 1 C with a C/2 hold.Some such cells, during the cycle stability phase, had periodic cyclesrun at C/10 between 2.5-4.2V with a C/5 hold (at a rate of once every 20cycles).

Example 13 Calculation for Mean Free Path for Deposition Gas

The mean free path (MFP) was calculated for a variety of differenttemperatures, pressures, and gases according to gas kinetic theory asknown in the art, for either 150 pm sized or 300 pm sized molecule (seeTable 11). Additional calculations are envisioned as known in the art.

TABLE 11 Example of mean free path calculation for deposition gas. GasMolecule Temperature Pressure MFP Size (C.) (kpa) (nm) 150 pm 400 10.12301 150 pm 400 101 231 150 pm 500 10.1 2643 150 pm 500 101 264 150 pm600 10.1 2985 150 pm 600 101 298 300 pm 400 10.1 575 300 pm 400 101 58300 pm 500 10.1 661 300 pm 500 101 66 300 pm 600 10.1 746 300 pm 600 10175

Example 14 Expansion Measurements of Various Anode Materials

Anodes were made following the procedures generally described herein.The anode material to be tested was typically diluted with graphite toachieve in the range of 400-700 mAh/g. The percent graphite in the blendfor each sample is described below, and in such cases the electrodeformulation generally consisted of 80% active materials (the material ingraphite blend), 10% conductivity enhancer such as SuperP, and 10%binder, such as SBR-CMC. In certain cases, the material was tested inthe absence of graphite, and such cases typically comprised 60% activatematerial, 20% conductivity enhancer, and 20% binder in the anodeformulation. In certain cases, the anode comprised 90% activatematerial, 5% conductivity enhancer, and 5% binder in the anodeformulation. The electrode used was 1M LiPF6 EC:DEC+10% FEC, and thelithium metal was used as a cathode to construct the half cell coincell. The cells were tested electrochemically as generally describedherein. The voltage was cycled from 0.8 V to 0.005 V at a C/10 rate for5 cycles followed by 25 cycles at C/5 rate. After the cycling, the coincells were brought to a 100% state of charge for a final time, thendissembled, and the anode thickness was measured compared to thestarting thickness before electrochemical testing. The different typesof samples produced were: graphite-based, carbon composited nanosilicon, carbon composited nano-featured silicon, carbon compositedsilicon oxide (SiOx), and a carbon silicon composite produced via silanedeposition on a porous carbon scaffold followed by a final carboncoating achieved via hydrocarbon chemical vapor deposition (C—Si—Ccomposited). Samples were produced according to general proceduresdescribed elsewhere herein. Also included are some samples comprisingbare nanosilicon, that is not composited with carbon. Unless otherwisestated, the capacity, either gravimetric or volumetric, refers to thecapacity of the non-lithiated material. These samples are summarized inthe Table 12 below.

The data for anode expansion vs. the gravimetric capacity are shown inFIG. 6 for non-composited (i.e., so-called bare) nanosilicon vs. thesame nanosilicon in a silicon carbon composite material. As can be seen,the bare material expands drastically with increasing gravimetriccapacity in the blend of nano silicon with graphite. In contrast, whenthe nanosilicon was composited with carbon, there was a dramaticallylowered expansion for the blend of carbon-composited nano silicon withgraphite. FIG. 7 shows the anode expansion vs. the gravimetric capacityfor a variety of different samples. The data are shown in FIG. 8 interms of anode expansion vs the volumetric capacity (in thenon-lithiated state). The carbon composited nanosilicon samples, thecarbon composited nanofeatured silicon samples, and the carboncomposited silicon oxide (SiOx) samples all showed similar expansionwith increasing gravimetric capacity in their respective blends withgraphite. In contrast, the surprising, unexpected finding was adramatically lower expansion for samples comprising a carbon siliconcomposite produced via silane deposition on a porous carbon scaffoldfollowed by a final carbon coating achieved via hydrocarbon chemicalvapor deposition (C—Si—C).

TABLE 12 Summary of samples for Example 14 Cou- Volu- Volu- Anode lombicExpan- metric metric Anode Anode Density First Effi- sion at Capacity,Capacity, Forumulation % Active (including Cycle Capacity ciency 100%delithiated lithiated (wt %:wt Graphite Material CE and Effi- @(avergage State of anode anode %:wt %) Ac- in Density binder) ciencyCycle 6 cycles Charge basis basis Material tive:CE:Binder Active (g/cm3)(g/cm3) (%) (mAh/g) 7-25) (%) (mAh/cm3) (mAh/cm3) Graphite sample 180:10:10 100 0.950 1.188 85.6% 358 0.9994 18% 340 302 Graphite sample 290:5:5  100 1.146 1.274 88.0% 353 Not det. 14% 405 310 Graphite sample 390:5:5  100 1.336 1.485 90.5% 359 0.9996 26% 480 286 Carbon-composited80:10:10 61 1.163 1.453 67.8% 600 0.9949 76% 697 342 silicon oxideSample 1 Carbon-composited 80:10:10 91 1.059 1.323 78.2% 456 0.9977 35%483 337 silicon oxide Sample 2 Carbon composited 80:10:10 91 0.927 1.15981.9% 462 0.9986 32% 428 351 nano-silicon Sample 1 Carbon composited80:10:10 91 0.967 1.209 80.3% 439 0.9968 37% 425 322 nano-silicon Sample1 Carbon composited 80:10:10 73 0.928 1.160 73.6% 570 0.9928 54% 529 371nano-silicon Sample 3 Carbon composited 80:10:10 71 0.987 1.234 75.2%583 0.9968 69% 575 344 nano-silicon Sample 4 Carbon composited 80:10:1070 0.998 1.248 73.4% 641 0.9933 78% 640 359 nano-silicon Sample 5 Carboncomposited 80:10:10 70 0.927 1.159 74.0% 547 0.9952 61% 507 339nano-silicon Sample 6 Carbon composited 80:10:10 70 0.853 1.066 73.1%589 0.9952 60% 502 369 nano-silicon Sample 7 Carbon composited 80:10:1070 0.864 1.080 73.9% 597 0.9955 53% 515 389 nano-silicon Sample 8 Carboncomposited 80:10:10 70 0.952 1.190 74.4% 648 0.9955 76% 617 368nano-silicon Sample 9 Carbon composited 80:10:10 58 0.876 1.095 75.6%597 0.9964 57% 523 382 nano-silicon Sample 10 Carbon composited 80:10:1070 0.845 1.056 72.7% 575 0.9945 62% 486 356 nano-silicon Sample 11Carbon composited 80:10:10 70 0.880 1.100 71.7% 550 0.9945 62% 484 340nano-silicon Sample 12 Carbon composited 80:10:10 70 1.004 1.255 73.7%610 0.9948 76% 612 346 nano-silicon Sample 13 Carbon composited 80:10:1085 0.824 1.030 79.0% 495 0.9924 43% 408 346 nano featured silicon Sample1 Carbon composited 80:10:10 70 1.010 1.263 73.2% 448 0.9955 45% 453 309nano featured silicon Sample 2 Carbon composited 80:10:10 70 1.092 1.36574.3% 536 0.9955 77% 585 303 nano featured silicon Sample 3 Carboncomposited 80:10:10 70 1.075 1.344 73.8% 592 0.9937 79% 636 330 nanofeatured silicon Sample 4 Carbon composited 80:10:10 85 0.812 1.01581.2% 484 0.9948 43% 393 339 nano featured silicon Sample 5 Carboncomposited 80:10:10 70 0.944 1.180 74.9% 549 0.9943 53% 518 359 nanofeatured silicon Sample 6 Carbon composited 80:10:10 70 0.946 1.18274.5% 511 0.9939 58% 483 324 nano featured silicon Sample 7 Carboncomposited 80:10:10 89.4 0.983 1.229 80.9% 428 0.9978 41% 421 305 nanofeatured silicon Sample 8 C—Si—C 80:10:10 70 0.754 0.942 77.8% 5190.9973 36% 392 382 composited Sample 1 C—Si—C 80:10:10 70 0.976 1.22080.0% 560 0.9985 26% 546 443 composited Sample 2 C—Si—C 60:20:20 0 0.5140.514 66.4% 692 1.0000 39% 356 497 composited Sample 3 C—Si—C 80:10:1076 0.877 1.096 73.0% 582 0.9976 29% 510 452 composited Sample 4 C—Si—C80:10:10 76 0.884 1.105 71.1% 528 0.9977 29% 467 411 composited Sample 5C—Si—C 80:10:10 65 0.830 1.038 76.6% 495 0.9997 29% 411 384 compositedSample 6 C—Si—C 80:10:10 65 0.830 1.038 Not Det. 546 0.9997 26% 453 433composited Sample 7 C—Si—C 80:10:10 58 0.410 0.513 79.4% 630 Not Det.26% 258 500 composited Sample 8 C—Si—C 80:10:10 70 0.920 1.150 89.1% 5090.9997 37% 468 372 composited Sample 9 C—Si—C 80:10:10 70 0.690 0.86380.9% 566 Not Det. 39% 391 407 composited Sample 10 Bare Nano Silicon80:10:10 93 0.947 1.184 76.6% 449 0.9951 58% 426 285 Sample 1 Bare NanoSilicon 80:10:10 74 0.769 0.962 67.4% 569 0.9893 77% 438 322 Sample 2Bare Nano Silicon 80:10:10 78 0.823 1.029 75.4% 581 0.9934 96% 479 297Sample 3 Bare Nano Silicon 80:10:10 76 0.892 1.116 74.9% 586 0.9933102%  523 290 Sample 4

Without being bound by theory, the lower expansion for the C—Si—Csamples translates into reduced propensity for material cracking anunstable SEI formation upon cycling in a battery. It is envisioned fromthe data the C—Si—C composite can exhibit, for example when blended withgraphite or another suitable matrix or when tested as a pure material,an anode expansion of less than 30% and a gravimetric capacity ofgreater than 400 mAh/g. In certain embodiments, the C—Si—C composite canexhibit an anode expansion of less than 30% and a gravimetric capacityof greater than 500 mAh/g. In certain embodiments, the C—Si—C compositecan exhibit an anode expansion of less than 30% and a gravimetriccapacity of greater than 600 mAh/g. In certain embodiments, the C—Si—Ccomposite can exhibit an anode expansion of less than 30% and agravimetric capacity of greater than 800 mAh/g. In certain embodiments,the C—Si—C composite can exhibit an anode expansion of less than 30% anda gravimetric capacity of greater than 1000 mAh/g.

In further embodiments, the C—Si—C composite can exhibit, for examplewhen blended with graphite or another suitable matrix or when tested asa pure material, an anode expansion of less than 40% and a gravimetriccapacity of greater than 500 mAh/g. In further embodiments, the C—Si—Ccomposite can exhibit an anode expansion of less than 40% and agravimetric capacity of greater than 600 mAh/g. In further embodiments,the C—Si—C composite can exhibit an anode expansion of less than 40% anda gravimetric capacity of greater than 800 mAh/g. In furtherembodiments, the C—Si—C composite can exhibit an anode expansion of lessthan 40% and a gravimetric capacity of greater than 1000 mAh/g.

In other embodiments, the C—Si—C composite can exhibit, for example whenblended with graphite or another suitable matrix or when tested as apure material, an anode expansion of less than 50% and a gravimetriccapacity of greater than 800 mAh/g. In other embodiments, the C—Si—Ccomposite can exhibit, for example when blended with graphite or anothersuitable matrix or when tested as a pure material, an anode expansion ofless than 60% and a gravimetric capacity of greater than 1000 mAh/g.

In some embodiments, the C—Si—C composite can exhibit, for example whenblended with graphite or another suitable matrix or when tested as apure material, an anode expansion of less than 20% and a gravimetriccapacity of greater than 500 mAh/g. In further embodiments, the C—Si—Ccomposite can exhibit an anode expansion of less than 20% and agravimetric capacity of greater than 600 mAh/g. In further embodiments,the C—Si—C composite can exhibit an anode expansion of less than 20% anda gravimetric capacity of greater than 800 mAh/g. In furtherembodiments, the C—Si—C composite can exhibit an anode expansion of lessthan 20% and a gravimetric capacity of greater than 1000 mAh/g.

FIG. 8 shows data for expansion vs. volumetric capacity for the samples.As can be seen, the carbon composited nanosilicon samples, the carboncomposited nanofeatured silicon samples, and the carbon compositedsilicon oxide (SiOx) samples all showed similar expansion withincreasing volumetric capacity in their respective blends with graphite.A highly surprising and unexpected finding was that the C—Si—C samplesshowed a highly flat dependence of expansion on the volumetric capacity.

Without being bound by theory, the lower expansion for the C—Si—Csamples translates into reduced propensity for material cracking anunstable SEI formation upon cycling in a battery. It is envisioned fromthe data the C—Si—C composite can exhibit, for example when blended withgraphite or another suitable matrix or when tested as a pure material,an anode expansion of less than 30% and a volumetric capacity of greaterthan 400 mAh/cm3. In certain embodiments, the C—Si—C composite canexhibit an anode expansion of less than 30% and a volumetric capacity ofgreater than 500 mAh/cm³. In certain embodiments, the C—Si—C compositecan exhibit an anode expansion of less than 30% and a volumetriccapacity of greater than 600 mAh/cm³. In certain embodiments, the C—Si—Ccomposite can exhibit an anode expansion of less than 30% and avolumetric capacity of greater than 800 mAh/cm³. In certain embodiments,the C—Si—C composite can exhibit an anode expansion of less than 30% anda volumetric capacity of greater than 1000 mAh/cm³.

In further embodiments, the C—Si—C composite can exhibit, for examplewhen blended with graphite or another suitable matrix or when tested asa pure material, an anode expansion of less than 40% and a volumetriccapacity of greater than 400 mAh/cm³. In certain embodiments, the C—Si—Ccomposite can exhibit an anode expansion of less than 40% and avolumetric capacity of greater than 500 mAh/cm³. In certain embodiments,the C—Si—C composite can exhibit an anode expansion of less than 40% anda volumetric capacity of greater than 600 mAh/cm³. In certainembodiments, the C—Si—C composite can exhibit an anode expansion of lessthan 40% and a volumetric capacity of greater than 800 mAh/cm³. Incertain embodiments, the C—Si—C composite can exhibit an anode expansionof less than 40% and a volumetric capacity of greater than 1000 mAh/cm³.

In further embodiments, the C—Si—C composite can exhibit, for examplewhen blended with graphite or another suitable matrix or when tested asa pure material, an anode expansion of less than 50% and a volumetriccapacity of greater than 400 mAh/cm³. In certain embodiments, the C—Si—Ccomposite can exhibit an anode expansion of less than 50% and avolumetric capacity of greater than 500 mAh/cm³. In certain embodiments,the C—Si—C composite can exhibit an anode expansion of less than 50% anda volumetric capacity of greater than 600 mAh/cm³. In certainembodiments, the C—Si—C composite can exhibit an anode expansion of lessthan 50% and a volumetric capacity of greater than 800 mAh/cm³. Incertain embodiments, the C—Si—C composite can exhibit an anode expansionof less than 50% and a volumetric capacity of greater than 1000 mAh/cm³.

Example 15 Cycling Data for Various Samples in a Li Ion Full Cell

Full cell coin cells were constructed for graphite, a carbon compositednano silicon samples, carbon-composited silicon oxide (SiOx) sample anda sample comprising a carbon silicon composite produced via silanedeposition on a porous carbon scaffold followed by a final carboncoating achieved via hydrocarbon chemical vapor deposition (C—Si—C). Thecathode material was NCA, and the electrolyte was 1M LiPF6 EC:DEC+10%FEC. The anode capacity was about 650 mAh/g as measured in a half cell.The cycling was accomplished at a rate of C/2, with a voltage windowbetween 2.0 and 4.2 V, and with a ½ hold. FIG. 9 depicts the cyclingstability data, in terms of the Wh/L relative to average data forgraphite. The Coulombic efficiency for the C—Si—C samples was0.9999+/−0.0016 (n=5 cells).

Example 16 Filling of Pores of Mixed Micro- and Mesoporous CarbonMaterials Via Silicon Deposition

A carbon comprising both micropores and mesopores (Carbon 13) wasexamined for its pore volume distribution before and after either 60 minor 120 min treatment with 2 mol % silane flowing at 380 sccm and 450° C.to create composite materials comprising silicon and carbon. The porevolume distributions of these samples are depicted in FIG. 10. As can beseen, there was a substantial decrease in the pore volume in themicropore range and the mesopore range consistent with filling ofmicropores and mesopores with silicon. The data show a more prominentdecrease in micropores compared the decrease in mesopore, indicating apreferential deposition of silicon favoring reduction of mesopores morethan micropores.

The same conclusion can be drawn from examining the data for the porevolume distribution for the various samples. The measured pore volumedistribution for the porous carbon scaffold comprised 41% siliconloading on the porous scaffold comprised 48% micropores, 52% mesopores,and 0% macropores. The measured pore volume distribution for the 60 minsilane-treated sample that resulted in 26% silicon loading on the porousscaffold comprised 45% micropores, 54% mesopores, and 1% macropores.These values are very similar to the starting scaffold. In contrast, themeasured pore volume distribution for the 120 min silane-treated samplethat resulted in 41% silicon loading on the porous scaffold comprised 5%micropores, 45% mesopores, and 50% macropores. In terms of percentreduction, the micropore volume for the 60 min silane-treated samplethat resulted in 26% silicon loading on the porous scaffold exhibited a58% reduction in micropore volume compared to the starting scaffold, andexhibited a 79% reduction in micropore volume compared to the startingscaffold. In terms of percent reduction, the micropore volume for the120 min silane-treated sample that resulted in 41% silicon loading onthe porous scaffold exhibited a 100% reduction in micropore volumecompared to the starting scaffold, and exhibited a 99% reduction inmicropore volume compared to the starting scaffold.

Example 17 Pycnometry Data Demonstrating the Capping of Microporeswithin a Microporous Carbon Scaffold Via Hydrocarbon CVD

A microporous carbon scaffold material was subject to treatment withhydrocarbon CVD generally according to the methodologies describedherein. Before the hydrocarbon CVD treatment, the measured surface area,pore volume and density via pycnometry were 1744 m²/g, 0.72 cm³/g and2.24 g/cm³, respectively. After the hydrocarbon CVD treatment, themeasured surface area, pore volume and density via pycnometry were 6m²/g, 0.701 cm³/g and 1.49 g/cm³, respectively. Without being bound bytheory, the dramatically lower surface area and pore volume, along withthe dramatically reduced skeletal density, are all consistent withcapping of carbon micropores. Accordingly, a hydrocarbon treatment orequivalent process known in the art are suitable for capping off carbonpores, for example carbon pores loaded with silicon deposited accordingto the principles generally described herein. Without being bound bytheory, such capping allows for internal porosity within the particle toaccommodate silicon expansion while minimizing the expansion of theenvelope volume of the particle.

Example 18 Effect of Porous Carbon Scaffold Particle Size on SilaneDeposition and Electrochemical Performance of the Resulting SiliconCarbon Scaffolds

A variety of pyrolyzed carbons with different particles sized andcomprising mixed micropores and mesopores were examined for theirsilicon deposition via silane gas as generally described herein. Thesamples included carbons that were granular (up to and exceeding 1 mm,as well as particles that were sized-reduced using either a FRITSCHPlanetary mill (FM) or jet mill (JM). The data are presented in Table13, including electrochemical testing in half cells as generallydescribed herein.

TABLE 13 Silicon carbon composites according to Example 18. SSA PV FCED50 Wt % Max Q Average Sample (m²/g) (cm³/g) (%) (um) Si (mAh/g) CE (%)Bare Carbon 645 0.61 N/A >1 mm 0 N/A N/A Granular 439 0.38 37 >1 mm 18604 N/A Si—C 2 min FM 164 0.12 55 101 33 1050 98.82 Si—C 5 min FM 1030.08 63 28 35 1200 99.36 Si—C Carbon 1 726 0.835 73 3.78 42 1554 99.63(JM) Carbon 679 0.544 79 3.8 41 1329 99.69 13 (JM)

As can be seen, all of the carbon scaffold particles tested, from thosewith Dv50 greater than 1 mm to those down to about 4 um, all werecapable of incorporating silicon via the silane deposition technique.There was a noticeable trend towards improved electrochemicalperformance (for example higher FCE and higher average CE) withdecreasing carbon scaffold particle size. Without being bound by theory,further reduction in carbon particle size would be likewise additionallybeneficial, for example Dv50 between 2 and 5 um, or Dv50 between 2 and 3um, or Dv50 between 1 and 3 um, or Dv50 between 1 and 2 um.Alternatively, it is envisioned that the carbon scaffold Dv50 willexhibit superior properties with respect to the current invention forcarbon scaffold particles exhibited Dv50 less than 1 um, and techniquesfor achieving the same are known in the art. For example, the carbonscaffold particle size can be between 0.1 and 1 um, for example between0.2 and 0.8 micron, for example between 0.4 and 0.6 um.

Example 19 Silicon Deposition Via Silane Decomposition on MacroporousCarbon Scaffolds and Electrochemical Performance of the ResultingSilicon Carbon Composites

A variety of different macroporous carbon scaffolds were treated withsilane to produce silicon carbon composites as generally describedherein. The data are presented in Table 14, including electrochemicaltesting in half cells as generally described herein.

TABLE 14 Silicon carbon composites according to Example 19. Duration ofSiH4 treat- TGA wt Post Post % Max Avg. CE ment (h) SSA PV % Si % O SSAPV FCE Q (7-25) 2 787 0.93 50 7 199 0.31 62 1742 97.27 2 939 0.977 57 5138 0.264 65 1848 97.52 2 1322 1.25 56 5 214 0.342 62 1653 97.72 2 19561.7 56 6 335 0.445 58 1758 97.7  1.5 787 0.93 43 7 787 0.93 N/A N/A N/A1.5 939 0.98 44 8 939 0.977 51 1339 97.88 1 787 0.93 28 2 335 0.445 N/AN/A N/A 1 939 0.977 33 11 426 0.576 35  764 97.77 1 1322 1.25 38 6 3450.488 N/A N/A N/A 1 1956 1.7 35 8 371 0.539 N/A N/A N/A

As can be seen, the macroporous carbon scaffold were capable of beingprocessed into silicon carbon composites via the silane treatmentgenerally described herein. However, the electrochemical properties ofthe silicon carbon composites produced from macroporous carbon scaffoldgenerally provides for relatively low first cycle efficiencies and lowaverage CE compared to analogous silicon carbon composites produced frommesoporous, microporous, or mixed micro- and mesoporous carbon scaffoldsas presented elsewhere herein.

Example 20 Silicon Deposition Via Silane Decomposition on Mixed Micro-and Mesoporous Carbon Scaffolds and Electrochemical Performance of theResulting Silicon Carbon Composites

A variety of different carbon scaffolds comprising micropores andmesopores were treated with silane to produce silicon carbon compositesas generally described herein. The data are presented in Table 15,including electrochemical testing in half cells as generally describedherein.

TABLE 15 Silicon carbon composites according to Example 20. Duration ofSiH4 treat- Scaffold Scaffold TGA wt Post Post % Max Avg. CE ment (h)SSA PV % Si % O SSA PV FCE Q (7-25) 2 763 0.58 45 1 2 0.003 75% 167399.3 2 1151 0.79 57 1 6 0.01 82% 2152 98.9 2 1860 1.21 58 3 131 0.11 78%2062 99 2 2273 1.47 54 8 274 0.22 71% 1833 99.3 1.5 763 0.58 39 2 310.029 70% 1318 99.41 1.5 1151 0.79 46 4 116 0.104 69% 1544 99.58 1 22731.47 34 8 779 0.56 37% 795 99.18 1 1151 0.79 32 7 329 0.27 50% 870 99.541 1860 1.21 35 7 520 0.41 44% 908 99.49 1 763 0.58 25 1 290 0.22 48% 76199.36

As can be seen, the carbon scaffolds comprising micropores and mesoporeswere capable of being processed into silicon carbon composites via thesilane treatment generally described herein. Importantly, theelectrochemical properties of the silicon carbon composites producedfrom carbon scaffolds comprising micropores and mesopores generallyprovides for higher average CE compared to analogous silicon carboncomposites produced from macroporous carbon scaffolds as presentedelsewhere herein.

Example 21 Effect of Carbon Scaffold Pyrolysis Temperature on SilaneDecomposition and Electrochemical Performance of the Resulting SiliconCarbon Composites

A carbon scaffold comprising micropores and mesopores was pyrolyzed atvarious temperatures, and subsequently were examined for their silicondeposition via silane gas as generally described herein. The samplesincluded carbons that were pyrolyzed at temperatures ranging from 500°C. to 1100° C. The data are presented in Table 16, includingelectrochemical testing in half cells as generally described herein.

TABLE 16 Silicon carbon composites according to Example 21. PyrolysisCarbon Carbon Post Post Temp Scaffold Scaffold TGA SSA PV % Max Q Avg.(C.) SSA PV % Si (m²/g) (cm³/g) FCE (mAh/g) CE 500 589 0.929 28% 3970.568 Not tested 700 770 1 42% 330 0.305 61% 1340 99.18 900 742 0.92 48%110 0.125 75% 1455 99.46 1100 679 0.895 44% 148 0.154 73% 1568 99.4

As can be seen, the carbon scaffold comprising micropores and mesoporesthat were pyrolyzed at various temperatures were capable of beingprocessed into silicon carbon composites via the silane treatmentgenerally described herein. However, the sample pyrolyzed at 500° C.exhibited a brown color and proved not suitable for processing into anelectrode for subsequent electrochemical testing. Importantly, theelectrochemical properties of the silicon carbon composites producedfrom carbon scaffolds comprising micropores and mesopores pyrolyzed atvarious temperatures demonstrated higher average CE with increasingpyrolysis temperatures. The higher pyrolysis temperatures also providedfor improved capacity retention (see FIG. 11).

Without being bound by theory, further higher pyrolysis temperatures areenvisioned to provide further improved electrochemical performance forthe silicon carbon composite, and said higher pyrolysis temperatures canbe reduced to practice as known in the art. For example, a preferredcarbon scaffold pyrolysis temperature is in excess of 800° C., forexample between 800 and 1200° C. Alternatively, the pyrolysistemperature can be between 900 and 1300° C., or between 1000 and 1400°C., or between 1100 and 1500° C., or between 1200 and 1600° C., orbetween 1300 and 1700° C. In some embodiments, the carbon scaffoldpyrolysis temperature can be in excess of 1700° C.

Example 22 Effect of Various Treatments to Porous Carbon and Influenceon Suitability as Scaffold for Creating Silicon Carbon Composites

A porous carbon scaffold comprising mixed micro- and mesoporous porestructures was subject to various treatments. These treatments includedheating in the presence of nitrogen at 1100, 1300, 1500, and 1700° C.,heating under the presence of hydrogen gas at 1100° C., heating underthe presence of ammonia gas at 900° C., or heating to 1300° C. in thepresence of N₂ following by heating to 550° C. in the presence of 1:2(w:w) carbon:HMT. The durations of the treatment were 60 min. A summaryof the treatments and the resulting physicochemical characteristics ofthe various treated carbon scaffolds are presented in Table 17, andtheir electrochemical performance in half cells are presented in Table18.

TABLE 17 Porous carbon scaffolds according to Example 22. SSA PV %Micro-, % meso-, Treatment (m²/g) (cm³/g) % macropores None 717 0.7727.7, 71.5, 0.8 1300 N₂ gas 527 0.68 20.45, 78.45, 1.1 1500 N₂ gas 4100.64 14.8, 83.8, 1.4 1700 N₂ gas 393 0.66 12.4, 86.7, 0.9 1100 H₂ gas679 0.544 42.9, 56.6, 0.5 900 NH3 gas 1656 1.01 53.1, 46.6, 0.3 1300 N₂gas + 179 0.402  6.1, 90.1, 3.8 550 C HMT

TABLE 18 Silicon carbon scaffolds according to Example 22. Cycle 20 Wt %Si SSA PV FCE Avg. retention Max Q Treatment Deposited (m²/g) (cm³/g)(%) CE (%) (mAh/g) None 39 214 0.18 64 99.54 97.2 1310 1300 N₂ gas 45 590.053 79 99.47 94.9 1668 1500 N₂ gas 41 88 0.13 76 99.14 95.4 1448 1700N₂ gas 30 166 0.27 62 99.26 98.1 957 1100 H₂ gas 41 4 0.002 79 99.6997.9 1329 900 NH₃ gas 60 4 0.004 82 98.82 79.5 2060 1300 N₂ gas + 46 4.60.007 79 99.65 99 1696 550 C HMT

As can be seen, for the treatments with nitrogen, there was a trendtowards decreased specific surface area and pore volume with increasingtemperatures. There was also a trend for decreased percentage microporevolume, and increased percentage mesopore volume. In the referencedembodiment, the porous carbon scaffold comprises a surface area of300-800 m²/g, between 10-30% micropores, 40-90% mesopores, and less than5% micropores.

For the sample treated with HMT, there was a surprising and unexpectedresult: dramatically decreased surface area and pore volume, decrease inpercent micropore volume, and increase in mesopore volume, even thoughthe temperature. Without being bound by theory, the above heattreatments and HMT treatment can be employed for producing a highsurface area carbon with very high percentage of mesopore volume. Forexample, carbons can be produced that exhibit a surface area of 100 to2000 m²/g and also exhibit less than 10% micropore volume and greaterthan 80% mesopore volume and less than 5% macropore volume. In otherembodiments, the carbon can exhibit a surface area of 100 to 1000 m²/gand also exhibit less than 10% micropore volume and greater than 90%mesopore volume and less than 5% macropore volume. In other embodiments,the carbon can exhibit a surface area of 100 to 1000 m²/g and alsoexhibit less than 5% micropore volume and greater than 90% mesoporevolume and less than 5% macropore volume. In other embodiments, thecarbon can exhibit a surface area of 100 to 500 m²/g and also exhibitless than 10% micropore volume and greater than 90% mesopore volume andless than 5% macropore volume. In other embodiments, the carbon canexhibit a surface area of 100 to 500 m²/g and also exhibit less than 5%micropore volume and greater than 90% mesopore volume and less than 5%macropore volume.

As can be seen from the electrochemical data, the highest average CEwere exhibited for the mixed micro- and mesoporous carbon scaffold thathad been heated to 1100° C. in the presence of hydrogen, and also thescaffold that had been treated with HMT at 55 C. The latter sample alsoexhibited the highest capacity retention.

Example 23 Effect of Different Carbon Scaffolds and the ResultingSilicon Carbon Composites

A variety of different carbon scaffolds were employed to produce siliconcarbon composites as generally describe herein employing silane as asilicon-containing reactant gas flowing at 580 sscm, 450° C. and 120 minconditions. Table 19 presents the various samples, Table 20 presents thephysicochemical for the resulting silicon carbon composites, and Table21 presents the electrochemical properties of the resulting siliconcarbon composites in half cells.

TABLE 19 Porous carbon scaffolds according to Example 23. SSA PV %Micro-, % meso-, Sample (m²/g) (cm³/g) % macropores Commercial graphiticcarbon 1 499 0.497 28, 64, 8 Commercial graphitic carbon 2 249 0.244 27, 39, 34 Commercial graphitic carbon 3 62 0.225  5, 48, 47 Commercialgraphitic carbon 4 393 0.66 12.4, 86.7, 0.9 Commercial graphitic carbon5 679 0.544 42.9, 56.6, 0.5 Micro-, mesoporous carbon 1 547 0.41 46, 53,1 Micro-, mesoporous carbon 2 694 0.48 49, 51, 0 Micro-, mesoporouscarbon 3 695 0.64 32, 68, 0 Micro-, mesoporous carbon 4 512 0.268 73,27, 0 Micro-, mesoporous carbon 5 616 0.303 42, 56, 2 Micro-, mesoporouscarbon 6 748 0.93 23, 77, 0 Micro-, mesoporous carbon 7 560 0.456 42,56, 2 Micro-, mesoporous carbon 8 1123 0.719 55, 45, 0 Micro-,mesoporous carbon 9 707 0.57 42, 58, 0 Macroporous carbon 1 693 0.817 17, 71, 12 Macroporous carbon 2 1114 1.017  24, 54, 22

TABLE 20 Physicochemical characteristics for silicon carbon scaffoldsaccording to Example 23. TGA Estimated wt % wt % SSA PV Treatmentsilicon Oxygen (m²/g) (cm³/g) Commercial graphitic carbon 1 44% N/A 360.076 Commercial graphitic carbon 2 43% N/A 61 0.114 Commercialgraphitic carbon 3 28% 0% 52 0.092 Commercial graphitic carbon 4 42% N/A21 0.048 Commercial graphitic carbon 5 20% N/A 91 0.114 Micro-,mesoporous carbon 1 31% 0% 4 0.005 Micro-, mesoporous carbon 2 33% N/A 10.001 Micro-, mesoporous carbon 3 44% 3% 29 0.021 Micro-, mesoporouscarbon 4 N/A N/A 1 0.001 Micro-, mesoporous carbon 5 N/A N/A 0.16 0.01Micro-, mesoporous carbon 6 53% N/A 19 0.021 Micro-, mesoporous carbon 737% N/A 4 0.008 Micro-, mesoporous carbon 8 46% 3% 13 0.006 Micro-,mesoporous carbon 9 35% 0% 173 0.099 Macroporous carbon 1 47% 5% 1730.266 Macroporous carbon 2 29% 5% 498 0.589

TABLE 21 Physicochemical Characteristics for Silicon Carbon ScaffoldsAccording to Example 23. Calc. TGA Si—C Max Silicon Capacity FCE Revers.Q SSA PV Capacity Li₁₅Si₄ Average Retention Treatment (%) (mAh/g) (m²/g)(cm³/g) (mAh/g) phase CE (%) @cycle 20 Commercial graphitic carbon 1 70%1531 36 0.076 3098 Yes 99.25 98.7 Commercial graphitic carbon 2 66% 169161 0.114 3667 No 98.33 97  Commercial graphitic carbon 3 57% 1150 520.092 3593 No 97.66 99.6 Commercial graphitic carbon 4 77% 1558 21 0.0483433 Yes 99.52 95.5 Commercial graphitic carbon 5 62%  764 91 0.114 3020No 99.49 99  Micro-, mesoporous carbon 1 76% 1297 4 0.005 3739 Yes 99.6794.3 Micro-, mesoporous carbon 2 70% 1174 1 0.001 3152 Yes 98.81 66.6Micro-, mesoporous carbon 3 76% 1684 29 0.021 3573 Yes 99.12 77.4Micro-, mesoporous carbon 4 N/A N/A 1 0.001 N/A N/A N/A N/A Micro-,mesoporous carbon 5 N/A N/A 0.16 0.01 N/A N/A N/A N/A Micro-, mesoporouscarbon 6 78% 1801 19 0.021 3221 Yes 99.48 87.8 Micro-, mesoporous carbon7 69% 1321 4 0.008 3230 Yes 99.21 84.3 Micro-, mesoporous carbon 8 76%1634 13 0.006 3317 No 98.93 67.7 Micro-, mesoporous carbon 9 65% 1145173 0.099 2900 No N/A N/A Macroporous carbon 1 64% 1636 173 0.266 3255No 98.82 91.2 Macroporous carbon 2 44%  897 498 0.589 2603 No 98.56 83.4

The data demonstrated the utility of the various types of carbonscaffolds (graphitic, micro- and mesoporous mixed, and macroporouscomprising) for their employment to produce silicon carbon composites.The electrochemical data include the calculated silicon capacity,employing the silicon content determined from TGA analysis, and assuminga carbon capacity of 200 mAh/g. Generally, the calculated siliconcapacity was in the range of 2500 to 4000 mAh/g. Also included in thetable above is information regarding whether there was the presence of adistinct peak centered at 0.44V vs. Li/Li+ in the differential capacity(dQ/dV) plot for the sample tested electrochemically in the half cell.This peak denotes the formation of the crystalline Li₁₅Si₄ alloy phaseindicating that the silicon present in the composite has been fullylithiated. Without being bound by theory, due to the detrimental effectsof phase boundaries (e.g., cracking) and stable crystalline structuresthat may be resistant to delithiation, a preferred Si—C compositeembodiment would not form this Li₁₅Si₄ throughout cycling therebyremaining amorphous.

Example 24 Creation of Silicon Carbon Scaffolds for Two or MoreDifferent Porous Carbon Scaffold Feedstocks Simultaneously Reacted withSilicon Containing Reactant

In some embodiments, a silicon carbon composite can be produced from twoor more porous carbon feedstocks that are reacted simultaneously (i.e.,in the same reactor) in the presence of a silicon containing reactant,for example silane. For the current example, a porous carbon scaffoldcomprising 763 m²/g specific surface area, 0.58 pore volume furthercomprised of 44% micropores, 55% mesopores and 1% macropores wascombined at a mass ratio of 4:1 with a second carbon scaffold, namelycommercial graphitic carbon 1. The 4:1 mixture of carbon scaffolds wasreacted with silane generally according to the processes describedherein. The first cycle efficiency for the composite produced from themixed micro- and mesoporous carbon scaffold, the composite produced fromthe graphitic carbon scaffold, and the composite produced from themixture of the two scaffolds, were 73%, 70% and 68%, respectively. Themaximum reversible capacity for the composite produced from the mixedmicro- and mesoporous carbon scaffold, the composite produced from thegraphitic carbon scaffold, and the composite produced from the mixtureof the two scaffolds, were 1554 mAh/g, 1531 mAh/g and 1415 mAh/g,respectively. The average Coulombic efficiency for the compositeproduced from the mixed micro- and mesoporous carbon scaffold, thecomposite produced from the graphitic carbon scaffold, and the compositeproduced from the mixture of the two scaffolds, were 0.9962, 0.9925 and0.9969, respectively. It was a surprising and unexpected result that theaverage Coulombic efficiency for the composite produced from the mixtureof scaffolds was higher than the composites produced from the individualcomponents.

Example 25 Effect of Subsequent Carbon Coating Via CVD on VariousSilicon Carbon Composites

A variety of different carbon scaffolds were employed to produce siliconcarbon composites as generally describe herein employing silane as asilicon-containing reactant gas. To example the effect of applying acarbon coating around the composite particle, the composite samples weresubjected to a CVD process wherein the composites were subject toelevated temperature in the presence of a carbon containing gas tocreate a carbonaceous coating. Table 22 presents the various samples andcarbon CVD conditions, Table 23 presents the physicochemical for theresulting carbon-coated silicon carbon composites, and Table 24 presentsthe electrochemical properties of the resulting carbon-coated siliconcarbon composites in half cells.

TABLE 22 Porous carbon scaffolds according to Example 25. CVD SSA PVSample and Scaffold conditions (m²/g) (cm³/g) Sample 25-1A None 787 0.93Pyrolyzed macroporous carbon Sample 25-1B 60 min, 800° C., Macroporouscarbon scaffold propane Sample 25-2A None 939 0.977 Activatedmacroporous carbon Sample 25-2B 60 min, 800° C., Activated macroporouscarbon propane Sample 25-3A None 1322 1.25 Activated macroporous carbonSample 25-3B 60 min, 800° C., Activated macroporous carbon propaneSample 25-4A None 1956 1.695 Activated macroporous carbon Sample 25-4B60 min, 800° C., Activated macroporous carbon propane Sample 25-5A None763 0.58 Mixed micro-, mesoporous carbon Sample 25-5B 30 min, 800° C.,Mixed micro-, mesoporous carbon propane Sample 25-5C 30 min, 1000° C.,Mixed micro-, mesoporous carbon methane Sample 25-6A None 499 0.497Commercial graphitic carbon 1 Sample 25-6B 30 min, 980° C., Commercialgraphitic carbon 1 propane Sample 25-6C 15 min, 980° C., Commercialgraphitic carbon 1 methane Sample 25-7A None 249 0.244 Commercialgraphitic carbon 2 Sample 25-7B 30 min, 980° C., Commercial graphiticcarbon 2 methane Sample 25-8A None 547 0.41 Pyrolyzed macroporous carbonSample 25-8B 30 min, 980° C., Pyrolyzed macroporous carbon methaneSample 25-9A None 694 0.48 Mixed micro-, mesoporous carbon viasuspension/emulsion processing Sample 25-9B 30 min, 980° C., Mixedmicro-, mesoporous carbon methane via suspension/emulsion processingSample 25-10A None 679 0.895 Mixed micro-, mesoporous carbon Frischmilled Sample 25-10B 30 min, 980° C., Mixed micro-, mesoporous carbonmethane Frisch milled Sample 25-11A None 688 0.545 Composite fromExample 24 Sample 25-11B 30 min, 980° C., Composite from Example 24methane Sample 25-12A None 683 0.537 Mixed micro-, mesoporous carbon,jet milled and treated at 1100° C. with nitrogen Sample 25-12B 30 min,980° C., Mixed micro-, mesoporous carbon, methane jet milled and treatedat 1100° C. with nitrogen Sample 25-13A None 679 0.544 Mixed micro-,mesoporous carbon, jet milled and treated at 1100° C. with hydrogenSample 25-13B 15 min, 980° C., Mixed micro-, mesoporous carbon, methanejet milled and treated at 1100° C. with hydrogen Sample 25-13C 60 min,700° C., Mixed micro-, mesoporous carbon, propylene jet milled andtreated at 1100° C. with hydrogen Sample 25-13D 60 min, 550° C., Mixedmicro-, mesoporous carbon, acetylene jet milled and treated at 1100° C.with hydrogen

TABLE 23 Physicochemical characteristics for silicon carbon compositesaccording to Example 25. SSA Pore Vol TGA. Si content Sample (m²/g)(cm³/g) (%) Sample 25-1A 199 0.31 31% Sample 25-1B 63 0.13 32% Sample25-2A 138 0.264 31% Sample 25-2B 38 0.085 28% Sample 25-3A 214 0.342 Notdetermined Sample 25-3B 65 0.139 44% Sample 25-4A 335 0.445 35% Sample25-4B 80 0.176 15% Sample 25-5A 7.5 0.0085 24% Sample 25-5B 7.7 0.01 Notdetermined Sample 25-5C 5 0.007 33% Sample 25-6A 36 0.076 25% Sample25-6B 15 0.026 25% Sample 25-6C 29 0.05 35% Sample 25-7A 61 0.114 Notdetermined Sample 25-7B 36 0.07 Not determined Sample 25-8A 4 0.005 31%Sample 25-8B 2 0.002 32% Sample 25-9A 1 0.001 31% Sample 25-9B 1 0.00128% Sample 25-10A 148 0.154 Not determined Sample 25-10B 61 0.037 44%Sample 25-11A 50 0.052 35% Sample 25-11B 4 0.005 15% Sample 25-12A 60.008 24% Sample 25-12B 1 0.004 Not determined Sample 25-13A 4 0.002 33%Sample 25-13B 4 0.004 25% Sample 25-13C Not determined Not determinedSample 25-13D Not determined Not determined

TABLE 24 Physicochemical characteristics for silicon carbon compositesaccording to Example 25. Calc. TGA Si—C Max Silicon Capacity FCE Revers.Q Capacity Li₁₅Si₄ Average Retention Sample (%) (mAh/g) (mAh/g) phase CE(%) @cycle 20 Sample 25-1A 62% 1742 3284 Yes 97.33 73.7 Sample 25-1B 62%912 2497 Yes 99.39 99 Sample 25-2A 65% 1848 3091 Yes 97.52 65.8 Sample25-2B 68% 1018 2756 Yes 99.49 94.5 Sample 25-3A 62% 1653 2795 Yes 97.7277.2 Sample 25-3B 61% 851 2300 Yes 99.41 97.5 Sample 25-4A 58% 1758 2982Yes 97.7 75.9 Sample 25-4B 56% 765 2218 Yes 99.28 96.2 Sample 25-5A 73%1554 3424 Yes 99.62 94.7 Sample 25-5B 70% 1170 ND Yes 99.76 91.1 Sample25-5C 69% 1115 2891 Yes 99.77 98.8 Sample 25-6A 70% 1531 3098 Yes 99.2598.7 Sample 25-6B 66% 719 2457 No 100 99.5 Sample 25-6C 72% 1015 2529Yes 99.59 98.7 Sample 25-7A 66% 1691 3667 No 98.33 96.9 Sample 25-7B 60%570 2667 No 99.41 97 Sample 25-8A 76% 1297 3739 Yes 99.67 94.3 Sample25-8B 68% 728 2400 Yes 99.65 99.1 Sample 25-9A 70% 1174 3152 Yes 98.8166.6 Sample 25-9B 60% 606 ND Yes 99.74 96.6 Sample 25-10A 73% 1568 3309Yes 99.4 92 Sample 25-10B 71% 1058 2800 Yes 99.77 99.1 Sample 25-11A 68%1415 ND No 99.69 96.9 Sample 25-11B 65% 719 2276 Yes 99.73 96.1 Sample25-12A 79% 1544 ND Yes 99.69 92.8 Sample 25-12B Not measured Sample25-13A 79% 1329 2954 Yes 99.69 97.9 Sample 25-13B 75% 1077 2706 Yes99.76 98 Sample 25-13C 77% 1192 ND Yes 99.69 95.7 Sample 25-13D 78% 1333ND Yes 99.69 97.2 ND = not determined

As can be seen, the various gases employed for CVD—methane, propane,acetylene, propylene all demonstrate utility as carbon-containing gasessuitable for employment in a CVD process to create a carbon coatedsilicon carbon scaffold. FIG. 12 depicts electrochemical datarepresenting non-coated (striped bars) vs coated (solid bars) for thesamples measured in half cells. As can be seen, the CVD carbon coatingprocess tends to provide for lower silicon capacity, and hence lowercapacity for the composite. Importantly, the data also show that the CVDcarbon coating allows for increased Coulombic efficiency, as well asincreased capacity retention. Without being bound by theory, theapplication of carbon coating via CVD of the silicon carbon compositeprovides for a structure barrier to the silicon to decrease or preventinto expansion beyond the envelope volume of the particle. In turn, thisrestriction of silicon expansion provides for the slightly lowercapacity observed, and is consistent with reduced exposure of silicon tothe electrolyte solvent, more stable SEI, improved Coulombic efficiency,and improved capacity retention upon cycling.

Example 26 Expansion Measurements of Anode Materials Comprising SiliconCarbon Composites

Anodes were made following the procedures generally described herein.The anode material to be tested typically comprised the sample to betested, as well as graphite and conductivity enhancer. The anodepreparation and half cell preparation and testing were carried out asgenerally described elsewhere in this disclosure. For this particularexample, data were considered for three sample groups. The first samplegroup comprised composites of nano silicon and carbon. The second samplegroup comprised silicon carbon composite material that was producedusing a porous carbon scaffold that comprised a Dv50 less than 5 micronsand a pore volume that comprised a mixture of micropores and mesopores,and wherein the silicon was created via deposition employing a siliconcontaining gas as described elsewhere herein, and wherein the siliconcarbon composite was carbon coated via CVD employing a carbon containinggas as generally described herein. The latter class of silicon carboncomposites is denoted as “Group14 Composite.”

FIG. 13 presents the data for the three sample groups, specifically thatdata are plotted for expansion as a function of the volumetric capacityat full lithiation (calculated from measured gravimetric expansion,electrode density, and anode volume expansion). As can be seen, the datafor the Group14 Composite group of silicon carbon composites distinctbehavior compared to the composites comprising nano-sized and carbon orcomposites comprising nano-featured silicon and carbon. Specifically,the Group14 silicon carbon composite exhibits a lower extent of volumeexpansion with increasing volumetric capacity at full lithiation.

The observations regarding expansion vs volumetric capacity at fulllithiation yielded a surprising and unexpected performance for theGroup14 composites. The Group14 composites were capable of comprising ananode with a volumetric capacity at full lithiation between 250 to 350mAh/cm³ with an anode expansion of less than 40%. Alternatively, theGroup14 composites were capable of comprising an anode with a volumetriccapacity at full lithiation between 250 to 350 mAh/cm³ with an anodeexpansion of less than 30%. Alternatively, the Group14 composites werecapable of comprising an anode with a volumetric capacity at fulllithiation between 250 to 350 mAh/cm³ with an anode expansion of lessthan 20%. Alternatively, the Group14 composites were capable ofcomprising an anode with a volumetric capacity at full lithiationbetween 350 to 450 mAh/cm³ with an anode expansion of less than 60%.Alternatively, the Group14 composites were capable of comprising ananode with a volumetric capacity at full lithiation between 350 to 450mAh/cm³ with an anode expansion of less than 50%. Alternatively, theGroup14 composites were capable of comprising an anode with a volumetriccapacity at full lithiation between 350 to 450 mAh/cm³ with an anodeexpansion of less than 40%. Alternatively, the Group14 composites werecapable of comprising an anode with a volumetric capacity at fulllithiation between 450 to 600 mAh/cm³ with an anode expansion of lessthan 40%. Alternatively, the Group14 composites were capable ofcomprising an anode with a volumetric capacity at full lithiationbetween 450 to 600 mAh/cm³ with an anode expansion of less than 100%.Alternatively, the Group14 composites were capable of comprising ananode with a volumetric capacity at full lithiation between 450 to 600mAh/cm³ with an anode expansion of less than 80%. Alternatively, theGroup14 composites were capable of comprising an anode with a volumetriccapacity at full lithiation between 450 to 600 mAh/cm³ with an anodeexpansion of less than 60%.

Example 27 Effect of Particle Size of Silicon Carbon Composite on FullCell Electrochemical Performance

Carbon scaffold material comprising a mixed micro- and mesoporous naturewas processed into silicon carbon composite employing asilicon-containing reactant, followed by carbon coating via CVD. Allprocessing was conducted as generally described elsewhere in thisdisclosure. Two distinct particle sizes were employed for the porouscarbon scaffold: a relatively smaller size of Dv50=4.4 um (thiscomposite is designated Sample 27-1) and a corresponding porous carbonscaffold of relatively larger size, Dv,50=22.4 um (designated Sample27-2). These two different sized materials were employed to produce twodifferent sized samples of silicon carbon composites, and saidcomposites were examined electrochemically in full cells as generallydescribed within this disclosure. The cycle life data for the full cellsare presented in FIG. 14. For this example, the cycling rate was 1 C,with C/10 cycles inserted every 20^(th) cycle. As can be seen, there wasa much greater stability, about a two-fold improvement for the siliconcarbon composite produced using the smaller size scaffold. Without beingbound by theory, the smaller scaffold particle size results in theimproved performance due to more facile access of the silicon-containingreactant during the silicon deposition process. Accordingly, the porouscarbon scaffold to be process, and the resulting silicon carboncomposite, are preferred to exhibit Dv,50 of less than 20 um, forexample less than 10 um, for example less than 5 um, for example lessthan 4 um, for example less than 3 um, for example less than 2 um, forexample less than 1 um.

Example 28 Effect of Carbon Coating of Silicon Carbon Composite on FullCell Electrochemical Performance

Carbon scaffold material comprising a mixed micro- and mesoporous natureand a Dv,50 of 4.4 um was processed into silicon carbon compositeemploying a silicon-containing reactant. All processing was conducted asgenerally described elsewhere in this disclosure. This sample (denotednon-carbon coated or non C-coated) was tested electrochemically in fullcells as generally described within this disclosure. The non-carboncoated silicon carbon composite is designated Sample 28-1 and thecarbon-coated silicon carbon composite is designated Sample 28-2. Forcomparison, the same silicon carbon scaffold was subject to an additionprocess of carbon coating via CVD as generally described herein. Thislatter sample (denoted carbon-coated or C-coated) was also testedelectrochemically in full cells as generally described within thisdisclosure.

The cycle life data for the full cells are presented in FIG. 15. For theC-coated sample, the cycling rate was 1 C, with C/10 cycles insertedevery 20^(th) cycle. For the non C-coated sample, the cycling rate was 1C. As can be seen, there was a much greater stability for the C-coatedsilicon carbon composite. Without being bound by theory, the additionalcarbon coating enveloping the silicon-carbon composite particle allowsfor reducing particle expansion and providing more favorable SEI.Accordingly, the silicon carbon composite particle comprises a terminalsurface layer of carbon that is 0.1 to 30% of the total mass of theparticle, for example 1-20% of the total mass of the particle, forexample 2 to 15% of the total mass of the particle, for example 3 to 10%of the total mass of the particle, for example 5-10% of the total massof the particle, for example 2 to 10% of the total mass of the particle,for example 0.1 to 10% of the total mass of the particle.

Example 29 Electrochemical Testing of C-Coated Silicon Carbon Composite

Carbon scaffold material comprising a mixed micro- and mesoporousnature, a total surface area of 763 m²/g and a total pore volume of 0.58cm³/g, and a Dv,50 of 4 um, was processed into silicon carbon compositeemploying a silicon-containing reactant. The reactant gas was 1.25 mol %silane in nitrogen flowing at 5780 sccm for 2 hours at 450° C.,resulting in 71% weight gain. The resulting silicon content for thesilicon carbon composite was 39-42% and the oxygen content was 1-2%. Forthe silicon carbon composite, the calculated percentage of carbon porevolume filled by the silicon was 54% and the calculated silicon volumeas a percentage of total composite volume was 35%.

After the silicon deposition process with silane, the resulting siliconcarbon composite had a total surface area of 75 m²/g and a total porevolume of 0.05 cm³/g. The next processing step was to apply a carboncoating by processing at 800° C. in the presence of propane, resultingin a 2% weight gain. The resulting C-coated silicon carbon composite had37% silicon content, a total surface area of 7.7 m²/g and a total porevolume of 0.011 cm³/g. For the silicon carbon composite, the calculatedpercentage of carbon pore volume filled by the silicon was 54% and thecalculated silicon volume as a percentage of total composite volume was35%. For the C-coated silicon carbon composite, the calculatedpercentage of carbon pore volume filled by the silicon was 52% and thecalculated silicon volume as a percentage of total composite volume was34%.

Accordingly, for either the silicon carbon composite or the C-coatedsilicon carbon composite, the calculated percentage of carbon porevolume filled by the silicon can be 10-90%, for example 20-80%, forexample 30-70%, for example 40-60%. Accordingly, for either the siliconcarbon composite or the C-coated silicon carbon composite, thecalculated silicon volume as a percentage of total composite volume canbe 10-90%, for example 20-80%, for example 30-70%, for example 30-60%,for example 30-50%, for example 30-40%.

The C-coated silicon carbon composite was tested electrochemically inhalf cells. The anode active material comprised 35:65 (w:w)C-coatedsilicon carbon composite:graphite, and said active was mixed with binderand conductivity enhancer, and calendared, all as generally describedelsewhere within this disclosure.

The first cycle efficiency was 69%, the maximum reversible capacity was1201 mAh/g, the calculated TGA silicon capacity was 2905 mAh/g, and theaverage Coulombic efficiency was 0.9967.

The C-coated silicon carbon composite anode was tested electrochemicallyin full cell, pouch cell format, employing methods generally describedherein. The data for percent capacity retention vs cycle are presentedin FIG. 16 (pouch cell cycling at 1 C with C/10 every 20^(th) cycle). Ascan be seen, the anode comprising C-coated silicon carbon composite wascapable of achieving 300-600 cycle stability, wherein cycle stability isdefined as the number of cycles before 20% capacity loss (or 80%capacity retention) is observed. Without being bound by theory,additional improvements on an anode and cell construction level can beachieved as known in the art to achieve further cycle stabilityimprovement. Accordingly, an anode comprising the C-coated siliconcarbon composite exhibits a cycle stability of 300-2000 cycles, forexample 400 to 2000 cycles, for example 500-2000 cycles, for example500-1500 cycles, for example 1000-1500 cycles, or, alternatively,1000-2000 cycles.

Data for gravimetric capacity on an anode active basis vs cycle arepresented in FIG. 17 (pouch cell cycling at C/2). As can be seen, theanode comprising C-coated silicon carbon composite was capable ofmaintaining above 400 mAh/g gravimetric capacity for greater than 400cycles. Without being bound by theory, additional improvements on ananode and cell construction level can be achieved as known in the art toachieve further improvement. Accordingly, an anode comprising theC-coated silicon carbon composite exhibits above 400 mAh/g gravimetriccapacity for greater than 500 cycles, for example greater than 600cycles, for example greater than 700 cycles, for example greater than800 cycles, for example greater than 1000 cycles, for example between1000 and 2000 cycles. Accordingly, an anode comprising the C-coatedsilicon carbon composite exhibits above 500 mAh/g gravimetric capacityfor greater than 500 cycles, for example greater than 600 cycles, forexample greater than 700 cycles, for example greater than 800 cycles,for example greater than 1000 cycles, for example between 1000 and 2000cycles. Accordingly, an anode comprising the C-coated silicon carboncomposite exhibits above 600 mAh/g gravimetric capacity for greater than500 cycles, for example greater than 600 cycles, for example greaterthan 700 cycles, for example greater than 800 cycles, for examplegreater than 1000 cycles, for example between 1000 and 2000 cycles.Accordingly, an anode comprising the C-coated silicon carbon compositeexhibits above 800 mAh/g gravimetric capacity for greater than 500cycles, for example greater than 600 cycles, for example greater than700 cycles, for example greater than 800 cycles, for example greaterthan 1000 cycles, for example between 1000 and 2000 cycles. Accordingly,an anode comprising the C-coated silicon carbon composite exhibits above1000 mAh/g gravimetric capacity for greater than 500 cycles, for examplegreater than 600 cycles, for example greater than 700 cycles, forexample greater than 800 cycles, for example greater than 1000 cycles,for example between 1000 and 2000 cycles, between 2000 and 3000 cycles,or greater than 3000 cycles.

Example 30 Rate Studies for Silicon Carbon Composite Materials

The rate capability of silicon carbon composite materials was comparedto graphite, as well as a silicon oxide (SiOx) material. All materialswere tested in half cells in a 60% active, 20% binder, and 20%conductivity enhancer formulation. The cycling was conducted for fivecycles each at a series of progressively increasing rate from C/10 toC/5 to C/2 to 1 C to 2 C. Two silicon carbon composites were tested, onecorresponding to the description of Sample 25-5B and the secondcorresponding to 25-6 A. The data for the gravimetric capacity arepresented in FIG. 18 in terms of mAh/g and in FIG. 19 in terms of % ofmaximum capacity observed at the slowest rate tested.

As can be seen, the silicon carbon composites disclosed herein providedsuperior rate performance, i.e., less propensity for capacity loss withincreasing cycling rate, compared to the silicon oxide comparator. Thesilicon carbon composites disclosed here were even capable of matchingthe rate profile of graphite, for example sample 25-6 A exhibits a verysimilar normalized capacity fade with increasing rate as was measuredfor graphite (see FIG. 19). This is a significant finding since graphiteis known in the art as a highly conductive material with suitable ratecapability for lithium ion batteries as anode materials. Even moresignificant, the silicon carbon composite materials disclosed hereinwere capable of many fold gravimetric improvement over graphite at allrates tested (see FIG. 18).

Accordingly, the present disclosure provides for a silicon carboncomposite material that when tested in a half cell at 2 C cycling rateis capable of achieving a gravimetric capacity of greater than 400mAh/g, for example, greater than 500 mAh/g, for example greater than 600mAh/g. It is envisioned that further improvements can be attained, forexample, providing for a silicon carbon composite material that whentested in a half cell at 2 C cycling rate is capable of achieving agravimetric capacity of greater than 700 mAh/g, for example greater than800 mAh/g, for example greater than 900 mAh/g, for example greater than1000 mAh/g.

Example 31 Effect of Densification on Electrochemical Performance ofVarious Materials

An anode comprising 35:65 w:w silicon carbon composite corresponding tothe description of Sample 25-5B:graphite was tested for electrochemicalperformance in full cell, coin cell format for varying degrees ofcalendaring of the anode. Specifically an anode was calendared atrelative low calendaring conditions, namely 19% calendaring to achieve afinal anode active density of 0.87 g/cm³, and also was also calendaredat relatively high calendaring conditions, namely 50% calendaring toachieve a final anode active density of 1.26 g/cm³. These data arepresented in FIG. 20.

For comparison, an anode comprising silicon oxide comparator (25:75 w:wcomparator:graphite) was also tested in full cell, coin cell format forvarying degrees of calendaring of the anode. Specifically an anode wascalendared at relative low calendaring conditions, namely 17.6%calendaring to achieve a final anode active density of 0.94 g/cm³, andalso was also calendared at relatively high calendaring conditions,namely 52% calendaring to achieve a final anode active density of 1.38g/cm³. These data are presented in FIG. 21.

As can be seen for the silicon oxide comparator, there was a dramaticreduction in cycle stability as the anode was densified from 0.94 g/cm³to 1.38 g/cm³, specifically, there was a 73% reduction in the cycle lifeobserved. Such a reduction in cycle life stability for asilicon-containing anode is expected as known in the art. As can be seenfor the novel silicon carbon composite disclosed herein, there wasexcellent cycle stability at both the low and high calendaringconditions (low and high anode density conditions) tested herein. Therewas only a slight drop, specifically, there was only 25% reduction incycle life observed. This finding is surprising and unexpected, giventhat the expectation in the art is reduced cycle life with increasinganode density.

Accordingly, anodes comprising the novel silicon carbon compositematerials disclosed herein are capable of achieving high cycle life incombination with high gravimetric capacity and high density. In certainembodiments, the current disclosure provides for an anode comprising thenovel silicon carbon composite material disclosed herein, wherein theanode exhibits a density greater than 1.0 g/cm³ and exhibits above 400mAh/g gravimetric capacity for greater than 500 cycles, for examplegreater than 600 cycles, for example greater than 700 cycles, forexample greater than 800 cycles, for example greater than 1000 cycles,for example between 1000 and 2000 cycles. Accordingly, an anodecomprising the novel silicon carbon composite material disclosed hereinexhibits a density greater than 1.0 g/cm³ and exhibits above 500 mAh/ggravimetric capacity for greater than 500 cycles, for example greaterthan 600 cycles, for example greater than 700 cycles, for examplegreater than 800 cycles, for example greater than 1000 cycles, forexample between 1000 and 2000 cycles. Accordingly, an anode comprisingthe novel silicon carbon composite material disclosed herein exhibits adensity greater than 1.0 g/cm³ and exhibits above 600 mAh/g gravimetriccapacity for greater than 500 cycles, for example greater than 600cycles, for example greater than 700 cycles, for example greater than800 cycles, for example greater than 1000 cycles, for example between1000 and 2000 cycles. Accordingly, an anode comprising the novel siliconcarbon composite material disclosed herein exhibits a density greaterthan 1.0 g/cm³ and exhibits above 800 mAh/g gravimetric capacity forgreater than 500 cycles, for example greater than 600 cycles, forexample greater than 700 cycles, for example greater than 800 cycles,for example greater than 1000 cycles, for example between 1000 and 2000cycles. Accordingly, an anode comprising the novel silicon carboncomposite material disclosed herein exhibits a density greater than 1.0g/cm³ and exhibits above 1000 mAh/g gravimetric capacity for greaterthan 500 cycles, for example greater than 600 cycles, for examplegreater than 700 cycles, for example greater than 800 cycles, forexample greater than 1000 cycles, for example between 1000 and 2000cycles.

In certain embodiments, the current disclosure provides for an anodecomprising the novel silicon carbon composite material disclosed herein,wherein the anode exhibits a density greater than 1.1 g/cm³ and exhibitsabove 400 mAh/g gravimetric capacity for greater than 500 cycles, forexample greater than 600 cycles, for example greater than 700 cycles,for example greater than 800 cycles, for example greater than 1000cycles, for example between 1000 and 2000 cycles. Accordingly, an anodecomprising the novel silicon carbon composite material disclosed hereinexhibits a density greater than 1.1 g/cm³ and exhibits above 500 mAh/ggravimetric capacity for greater than 500 cycles, for example greaterthan 600 cycles, for example greater than 700 cycles, for examplegreater than 800 cycles, for example greater than 1000 cycles, forexample between 1000 and 2000 cycles. Accordingly, an anode comprisingthe novel silicon carbon composite material disclosed herein exhibits adensity greater than 1.1 g/cm³ and exhibits above 600 mAh/g gravimetriccapacity for greater than 500 cycles, for example greater than 600cycles, for example greater than 700 cycles, for example greater than800 cycles, for example greater than 1000 cycles, for example between1000 and 2000 cycles. Accordingly, an anode comprising the novel siliconcarbon composite material disclosed herein exhibits a density greaterthan 1.1 g/cm³ and exhibits above 800 mAh/g gravimetric capacity forgreater than 500 cycles, for example greater than 600 cycles, forexample greater than 700 cycles, for example greater than 800 cycles,for example greater than 1000 cycles, for example between 1000 and 2000cycles. Accordingly, an anode comprising the novel silicon carboncomposite material disclosed herein exhibits a density greater than 1.1g/cm³ and exhibits above 1000 mAh/g gravimetric capacity for greaterthan 500 cycles, for example greater than 600 cycles, for examplegreater than 700 cycles, for example greater than 800 cycles, forexample greater than 1000 cycles, for example between 1000 and 2000cycles.

In certain embodiments, the current disclosure provides for an anodecomprising the novel silicon carbon composite material disclosed herein,wherein the anode exhibits a density greater than 1.2 g/cm³ and exhibitsabove 400 mAh/g gravimetric capacity for greater than 500 cycles, forexample greater than 600 cycles, for example greater than 700 cycles,for example greater than 800 cycles, for example greater than 1000cycles, for example between 1000 and 2000 cycles. Accordingly, an anodecomprising the novel silicon carbon composite material disclosed hereinexhibits a density greater than 1.2 g/cm³ and exhibits above 500 mAh/ggravimetric capacity for greater than 500 cycles, for example greaterthan 600 cycles, for example greater than 700 cycles, for examplegreater than 800 cycles, for example greater than 1000 cycles, forexample between 1000 and 2000 cycles. Accordingly, an anode comprisingthe novel silicon carbon composite material disclosed herein exhibits adensity greater than 1.2 g/cm³ and exhibits above 600 mAh/g gravimetriccapacity for greater than 500 cycles, for example greater than 600cycles, for example greater than 700 cycles, for example greater than800 cycles, for example greater than 1000 cycles, for example between1000 and 2000 cycles. Accordingly, an anode comprising the novel siliconcarbon composite material disclosed herein exhibits a density greaterthan 1.2 g/cm³ and exhibits above 800 mAh/g gravimetric capacity forgreater than 500 cycles, for example greater than 600 cycles, forexample greater than 700 cycles, for example greater than 800 cycles,for example greater than 1000 cycles, for example between 1000 and 2000cycles. Accordingly, an anode comprising the novel silicon carboncomposite material disclosed herein exhibits a density greater than 1.2g/cm³ and exhibits above 1000 mAh/g gravimetric capacity for greaterthan 500 cycles, for example greater than 600 cycles, for examplegreater than 700 cycles, for example greater than 800 cycles, forexample greater than 1000 cycles, for example between 1000 and 2000cycles.

In certain embodiments, the current disclosure provides for an anodecomprising the novel silicon carbon composite material disclosed herein,wherein the anode exhibits a density greater than 1.3 g/cm³ and exhibitsabove 400 mAh/g gravimetric capacity for greater than 500 cycles, forexample greater than 600 cycles, for example greater than 700 cycles,for example greater than 800 cycles, for example greater than 1000cycles, for example between 1000 and 2000 cycles. Accordingly, an anodecomprising the novel silicon carbon composite material disclosed hereinexhibits a density greater than 1.3 g/cm³ and exhibits above 500 mAh/ggravimetric capacity for greater than 500 cycles, for example greaterthan 600 cycles, for example greater than 700 cycles, for examplegreater than 800 cycles, for example greater than 1000 cycles, forexample between 1000 and 2000 cycles. Accordingly, an anode comprisingthe novel silicon carbon composite material disclosed herein exhibits adensity greater than 1.3 g/cm³ and exhibits above 600 mAh/g gravimetriccapacity for greater than 500 cycles, for example greater than 600cycles, for example greater than 700 cycles, for example greater than800 cycles, for example greater than 1000 cycles, for example between1000 and 2000 cycles. Accordingly, an anode comprising the novel siliconcarbon composite material disclosed herein exhibits a density greaterthan 1.3 g/cm³ and exhibits above 800 mAh/g gravimetric capacity forgreater than 500 cycles, for example greater than 600 cycles, forexample greater than 700 cycles, for example greater than 800 cycles,for example greater than 1000 cycles, for example between 1000 and 2000cycles. Accordingly, an anode comprising the novel silicon carboncomposite material disclosed herein exhibits a density greater than 1.3g/cm³ and exhibits above 1000 mAh/g gravimetric capacity for greaterthan 500 cycles, for example greater than 600 cycles, for examplegreater than 700 cycles, for example greater than 800 cycles, forexample greater than 1000 cycles, for example between 1000 and 2000cycles.

In certain embodiments, the current disclosure provides for an anodecomprising the novel silicon carbon composite material disclosed herein,wherein the anode exhibits a density greater than 1.4 g/cm³ and exhibitsabove 400 mAh/g gravimetric capacity for greater than 500 cycles, forexample greater than 600 cycles, for example greater than 700 cycles,for example greater than 800 cycles, for example greater than 1000cycles, for example between 1000 and 2000 cycles. Accordingly, an anodecomprising the novel silicon carbon composite material disclosed hereinexhibits a density greater than 1.4 g/cm³ and exhibits above 500 mAh/ggravimetric capacity for greater than 500 cycles, for example greaterthan 600 cycles, for example greater than 700 cycles, for examplegreater than 800 cycles, for example greater than 1000 cycles, forexample between 1000 and 2000 cycles. Accordingly, an anode comprisingthe novel silicon carbon composite material disclosed herein exhibits adensity greater than 1.4 g/cm³ and exhibits above 600 mAh/g gravimetriccapacity for greater than 500 cycles, for example greater than 600cycles, for example greater than 700 cycles, for example greater than800 cycles, for example greater than 1000 cycles, for example between1000 and 2000 cycles. Accordingly, an anode comprising the novel siliconcarbon composite material disclosed herein exhibits a density greaterthan 1.4 g/cm³ and exhibits above 800 mAh/g gravimetric capacity forgreater than 500 cycles, for example greater than 600 cycles, forexample greater than 700 cycles, for example greater than 800 cycles,for example greater than 1000 cycles, for example between 1000 and 2000cycles. Accordingly, an anode comprising the novel silicon carboncomposite material disclosed herein exhibits a density greater than 1.4g/cm³ and exhibits above 1000 mAh/g gravimetric capacity for greaterthan 500 cycles, for example greater than 600 cycles, for examplegreater than 700 cycles, for example greater than 800 cycles, forexample greater than 1000 cycles, for example between 1000 and 2000cycles.

In certain embodiments, the current disclosure provides for an anodecomprising the novel silicon carbon composite material disclosed herein,wherein the anode exhibits a density greater than 1.6 g/cm³ and exhibitsabove 400 mAh/g gravimetric capacity for greater than 500 cycles, forexample greater than 600 cycles, for example greater than 700 cycles,for example greater than 800 cycles, for example greater than 1000cycles, for example between 1000 and 2000 cycles. Accordingly, an anodecomprising the novel silicon carbon composite material disclosed hereinexhibits a density greater than 1.6 g/cm³ and exhibits above 500 mAh/ggravimetric capacity for greater than 500 cycles, for example greaterthan 600 cycles, for example greater than 700 cycles, for examplegreater than 800 cycles, for example greater than 1000 cycles, forexample between 1000 and 2000 cycles. Accordingly, an anode comprisingthe novel silicon carbon composite material disclosed herein exhibits adensity greater than 1.6 g/cm³ and exhibits above 600 mAh/g gravimetriccapacity for greater than 500 cycles, for example greater than 600cycles, for example greater than 700 cycles, for example greater than800 cycles, for example greater than 1000 cycles, for example between1000 and 2000 cycles. Accordingly, an anode comprising the novel siliconcarbon composite material disclosed herein exhibits a density greaterthan 1.6 g/cm³ and exhibits above 800 mAh/g gravimetric capacity forgreater than 500 cycles, for example greater than 600 cycles, forexample greater than 700 cycles, for example greater than 800 cycles,for example greater than 1000 cycles, for example between 1000 and 2000cycles. Accordingly, an anode comprising the novel silicon carboncomposite material disclosed herein exhibits a density greater than 1.6g/cm³ and exhibits above 1000 mAh/g gravimetric capacity for greaterthan 500 cycles, for example greater than 600 cycles, for examplegreater than 700 cycles, for example greater than 800 cycles, forexample greater than 1000 cycles, for example between 1000 and 2000cycles.

In certain embodiments, the current disclosure provides for an anodecomprising the novel silicon carbon composite material disclosed herein,wherein the anode exhibits a density greater than 1.8 g/cm³ and exhibitsabove 400 mAh/g gravimetric capacity for greater than 500 cycles, forexample greater than 600 cycles, for example greater than 700 cycles,for example greater than 800 cycles, for example greater than 1000cycles, for example between 1000 and 2000 cycles. Accordingly, an anodecomprising the novel silicon carbon composite material disclosed hereinexhibits a density greater than 1.8 g/cm³ and exhibits above 500 mAh/ggravimetric capacity for greater than 500 cycles, for example greaterthan 600 cycles, for example greater than 700 cycles, for examplegreater than 800 cycles, for example greater than 1000 cycles, forexample between 1000 and 2000 cycles. Accordingly, an anode comprisingthe novel silicon carbon composite material disclosed herein exhibits adensity greater than 1.8 g/cm³ and exhibits above 600 mAh/g gravimetriccapacity for greater than 500 cycles, for example greater than 600cycles, for example greater than 700 cycles, for example greater than800 cycles, for example greater than 1000 cycles, for example between1000 and 2000 cycles. Accordingly, an anode comprising the novel siliconcarbon composite material disclosed herein exhibits a density greaterthan 1.8 g/cm³ and exhibits above 800 mAh/g gravimetric capacity forgreater than 500 cycles, for example greater than 600 cycles, forexample greater than 700 cycles, for example greater than 800 cycles,for example greater than 1000 cycles, for example between 1000 and 2000cycles. Accordingly, an anode comprising the novel silicon carboncomposite material disclosed herein exhibits a density greater than 1.8g/cm³ and exhibits above 1000 mAh/g gravimetric capacity for greaterthan 500 cycles, for example greater than 600 cycles, for examplegreater than 700 cycles, for example greater than 800 cycles, forexample greater than 1000 cycles, for example between 1000 and 2000cycles.

Example 32 Pore Structures of Various Carbon Scaffolds and SiliconCarbon Materials

Carbon scaffolds and silicon carbon composites made therefore accordingto Example 19 and Example 20 were analyzed by nitrogen sorption fortheir pore structure. For the purpose of the current example, distinctranges of pore sizes were analyzed, according to their relevance fordeposition and containment of silicon to achieve suitable stability uponcycles of lithiation and delithiation. Specifically, pores ranging from50 to 200 A and pores below 200 A were analyzed. The data are presentedin Table 25.

TABLE 25 Sample and pore volumes according to Example 32. % of % of PoreVol- Pore Vol- Sample Type/Description ume 50-200 A ume <200 A Si—CComposite according to Ex. 20-1  8%  8% Si—C Composite according to Ex.20-2 27% 35% Si—C Composite according to Ex. 20-3 46% 96% Si—C Compositeaccording to Ex. 20-4 44% 97% Si—C Composite according to Ex. 20-5 29%74% Si—C Composite according to Ex. 20-6 47% 94% Si—C Compositeaccording to Ex. 20-7 39% 98% Si—C Composite according to Ex. 20-8 46%97% Si—C Composite according to Ex. 20-9 44% 98% Si—C Compositeaccording to Ex. 20-10 37% 97% Carbon scaffold according to Ex. 19-1 12%22% Carbon scaffold according to Ex. 19-2 12% 25% Carbon scaffoldaccording to Ex. 19-3 12% 27% Carbon scaffold according to Ex. 19-4 12%30% Carbon scaffold according to Ex. 20-1 42% 97% Carbon scaffoldaccording to Ex. 20-2 38% 98% Carbon scaffold according to Ex. 20-3 34%98% Carbon scaffold according to Ex. 20-4 33% 99%

Without being bound by theory, a preferred porous carbon scaffold fordeposition of silicon is such that the porous carbon scaffold comprisespores reside within the range of 50-200 A. Further preferred is a levelof said pores such that the pore can be partially filled within silicon,in order to provide additional void volume to allow for siliconexpansion and contraction upon cycling between lithiation andde-lithiation in a lithium ion battery.

Accordingly, the porous carbon scaffold comprises 10-50% of porescorresponding to 50-200 A, for example 12-42% of pores corresponding to50-200 A, for example 30-50% of pores corresponding to 50-200 A, forexample 30-40% of pores corresponding to 50-200 A. In certainembodiments, the porous carbon scaffold comprises 10-50% of porescorresponding to 50-200 A and greater than 90% of pores corresponding toless than 200 A. In certain embodiments, the porous carbon scaffoldcomprises 12-42% of pores corresponding to 50-200 A and greater than 90%of pores corresponding to less than 200 A. In certain embodiments, theporous carbon scaffold comprises 30-50% of pores corresponding to 50-200A and greater than 90% of pores corresponding to less than 200 A. Incertain embodiments, the porous carbon scaffold comprises 30-40% ofpores corresponding to 50-200 A and greater than 90% of porescorresponding to less than 200 A.

In certain embodiments, the porous carbon scaffold comprises 10-50% ofpores corresponding to 50-200 A, greater than 90% of pores correspondingto less than 200 A, and a total pore volume of 0.4 to 1.8 cm³/g. Incertain embodiments, the porous carbon scaffold comprises 12-42% ofpores corresponding to 50-200 A, greater than 90% of pores correspondingto less than 200 A, and a total pore volume of 0.4 to 1.8 cm³/g. Incertain embodiments, the porous carbon scaffold comprises 30-50% ofpores corresponding to 50-200 A, greater than 90% of pores correspondingto less than 200 A, and a total pore volume of 0.4 to 1.8 cm³/g. Incertain embodiments, the porous carbon scaffold comprises 30-40% ofpores corresponding to 50-200 A, greater than 90% of pores correspondingto less than 200 A, and a total pore volume of 0.4 to 1.8 cm³/g.

In certain embodiments, the porous carbon scaffold comprises 10-50% ofpores corresponding to 50-200 A, greater than 90% of pores correspondingto less than 200 A, and a total pore volume of 0.4 to 1.0 cm³/g. Incertain embodiments, the porous carbon scaffold comprises 12-42% ofpores corresponding to 50-200 A, greater than 90% of pores correspondingto less than 200 A, and a total pore volume of 0.4 to 1.0 cm³/g. Incertain embodiments, the porous carbon scaffold comprises 30-50% ofpores corresponding to 50-200 A, greater than 90% of pores correspondingto less than 200 A, and a total pore volume of 0.4 to 1.0 cm³/g. Incertain embodiments, the porous carbon scaffold comprises 30-40% ofpores corresponding to 50-200 A, greater than 90% of pores correspondingto less than 200 A, and a total pore volume of 0.4 to 1.0 cm³/g.

In certain embodiments, the porous carbon scaffold comprises 10-50% ofpores corresponding to 50-200 A, greater than 90% of pores correspondingto less than 200 A, and a total pore volume of 0.4 to 0.8 cm³/g. Incertain embodiments, the porous carbon scaffold comprises 12-42% ofpores corresponding to 50-200 A, greater than 90% of pores correspondingto less than 200 A, and a total pore volume of 0.4 to 0.8 cm³/g. Incertain embodiments, the porous carbon scaffold comprises 30-50% ofpores corresponding to 50-200 A, greater than 90% of pores correspondingto less than 200 A, and a total pore volume of 0.4 to 0.8 cm³/g. Incertain embodiments, the porous carbon scaffold comprises 30-40% ofpores corresponding to 50-200 A, greater than 90% of pores correspondingto less than 200 A, and a total pore volume of 0.4 to 0.8 cm³/g.

In certain embodiments, the porous carbon scaffold comprises 10-50% ofpores corresponding to 50-200 A, greater than 90% of pores correspondingto less than 200 A, and a total pore volume of 0.4 to 0.6 cm³/g. Incertain embodiments, the porous carbon scaffold comprises 12-42% ofpores corresponding to 50-200 A, greater than 90% of pores correspondingto less than 200 A, and a total pore volume of 0.4 to 0.6 cm³/g. Incertain embodiments, the porous carbon scaffold comprises 30-50% ofpores corresponding to 50-200 A, greater than 90% of pores correspondingto less than 200 A, and a total pore volume of 0.4 to 0.6 cm³/g. Incertain embodiments, the porous carbon scaffold comprises 30-40% ofpores corresponding to 50-200 A, greater than 90% of pores correspondingto less than 200 A, and a total pore volume of 0.4 to 0.6 cm³/g.

Example 33 Specific Density and Volume Measurements for Porous CarbonScaffold and Silicon Carbon Composites Produced Therefrom

The materials pertaining to the current example include the porouscarbon scaffold according to Example 27 wherein the porous carbonexhibited a Dv,50 of 22.4 um, the silicon carbon composite according toExample 27 wherein the porous carbon scaffold employed to produce saidcomposite exhibited a Dv,50 of 22.4 um, and third sample produced byemploying CVD processes described generally herein to produce acarbon-coated silicon carbon composite according to Example 27 whereinthe porous carbon scaffold employed to produced said carbon-coatedcomposite exhibited a Dv,50 of 22.4 um.

For the above samples, the following data were measured: skeletaldensity (by helium pycnometry), total pore volume (by nitrogensorption), and pellet density (by measuring the weight and volume of apellet produced by compressing the material under up to 2000 kg/cm²).From these data, the following parameters were calculated: the skeletalvolume (inverse of the skeletal density), the total envelope volume (sumof skeletal specific volume and total pore volume), and the envelopedensity (inverse of the envelope volume). The data and calculations aresummarized in Table 26.

TABLE 26 Volume and density measurements for porous carbon scaffold,silicon carbon composite and carbon-coated silicon composite.Theoretical Skeletal Skeletal Pore Envelope Envelope Pellet PelletDensity Volume Volume Volume Density Density Density Sample (g/cm3)(cm³/g) (cm³/g) (cm³/g) (g/cm³) (g/cm³) (g/cm³) Porous carbon 1.97 0.5080.579 1.087 0.920 0.70 0.68 scaffold Silicon carbon 2.15 0.465 0.0030.468 2.14 1.58 1.04 composite Carbon-coated 1.65 0.606 <0.001 0.6061.65 1.22 1.09 silicon carbon composite

The following are notes to Table 26: skeletal density was measured byhelium pycnometry; skeletal volume was determined as the inverse of theskeletal density; pore volume was determined from nitrogen sorption;envelope volume was calculated as the sum of the skeletal volume and thepore volume; the envelope density was determined as the inverse of thetotal envelope volume; the pellet density was calculated from themeasured mass and volume of the material after pressing it into a pelletat a force of 2000 kg/cm²; the theoretical pellet density was calculatedas 0.74048 multiplied by the envelope density.

For the carbon scaffold, the measured skeletal density was 1.97 g/cm³.The calculated skeletal volume was 0.508 cm³/g. For the carbon scaffold,the measured total pore volume was 0.579 cm³/g. For the carbon scaffold,the calculated total envelope volume was 1.087 cm³/g. For the carbonscaffold, the calculated envelope density was 0.920. Without being boundby theory, assuming the carbon particles are spherical in shape, themaximum packing density would be 0.74048 as known in the art.Accordingly, the maximally compress material would theoretically have apellet density of 0.68 g/cm². This value is very similar to the measuredpellet density of 0.70 cm²/g.

For the silicon carbon composite, the measured skeletal density was 2.15g/cm³. The measured silicon content was 39%. Without being bound bytheory, assuming the skeletal density of the carbon was unchanged andthe silicon density was 2.33 g/cm² (as known in the art) and employingthe measured content of silicon and carbon by difference, thetheoretical calculated silicon composite skeletal density is 2.11 g/cm³,very similar to the measured value of 2.15 cm³/g. For the silicon carboncomposite, the calculated skeletal volume was 0.465 cm³/g. For thesilicon carbon composite, the measured total pore volume was 0.003cm³/g. For the silicon carbon composite, the calculated total envelopevolume was 0.468 cm³/g. For the silicon carbon composite, the calculatedenvelope density was 2.14 g/cm³. Without being bound by theory, assumingthe carbon particles are spherical in shape, the maximum packing densitywould be 0.74048 as known in the art. Accordingly, the maximallycompress material would theoretically have a pellet density of 1.58g/cm³. A surprising and unexpected result was that this value, namely1.58 g/cm³, was much higher than the measured pellet density of thesilicon carbon composite, namely 1.04 g/cm³. Without being bound bytheory, this unexpected finding indicates that volume exists within thesilicon carbon composite particle that is not accessible by nitrogen.The calculated hidden or nitrogen-inaccessible pore volume, orV(nitrogen inaccessible), from the data was determined according to theequation: V(nitrogen inaccessible)=[0.7404/(measured pelletdensity)-(skeletal volume)-(pore volume determined by nitrogen). Fromthis equation, the nitrogen-inaccessible volume was determined to be0.244 cm³/g.

For the carbon-coated silicon carbon composite, the measured skeletaldensity was 1.65 g/cm³. The measured silicon content was 39%. Withoutbeing bound by theory, assuming the skeletal density of the carbon wasunchanged and the silicon density was 2.33 g/cm³ (as known in the art)and employing the measured content of silicon and carbon by difference,the theoretical calculated silicon composite skeletal density is 2.11g/cm³, much higher than the measured value of 1.65 g/cm³. Without beingbound by theory, the carbon coating has resulted in volume existingwithin the silicon carbon composite that is not accessible by helium.For the carbon-coated silicon carbon composite, the calculated skeletalvolume was 0.606 cm³/g. For the carbon-coated silicon carbon composite,the measured total pore volume by nitrogen sorption was negligible (lessthan 0.001 cm³/g). For the carbon-coated silicon carbon composite, thecalculated total envelope volume was 0.606 cm³/g. For the carbon-coatedsilicon carbon composite, the calculated envelope density was 1.65g/cm³. Without being bound by theory, assuming the carbon particles arespherical in shape, the maximum packing density would be 0.74048 asknown in the art. Accordingly, the maximally compress material wouldtheoretically have a pellet density of 1.22 g/cm³. A surprising andunexpected result was that this value, namely 1.22 g/cm³, was muchhigher than the measured pellet density of the silicon carbon composite,namely 1.09 g/cm³. Without being bound by theory, this unexpectedfinding indicates that volume exists within the silicon carbon compositeparticle that is not accessible by nitrogen. The calculated hidden porevolume, or nitrogen-inaccessible pore volume from the data wasdetermined to 0.072 cm³/g.

Accordingly, the present invention allows for a novel silicon carboncomposite, wherein the pellet density ranges from 1.0 to 1.5 g/cm³, theskeletal density as measured by helium pycnometry ranges from 1.9 to 2.2g/cm³, the skeletal volume as measured by helium pycnometry ranges from0.454 to 0.526 cm³/g, and the nitrogen-inaccessible volume ranges from0.2 to 0.3 cm³/g. Alternatively, the above elements are combined with anitrogen-inaccessible volume ranging from 0.1 to 0.5 cm³/g, or 0.2 to0.4 cm³/g, or 0.1 to 0.3 cm³/g, or 0.3 to 0.5 cm³/g.

Accordingly, the present invention allows for a novel carbon-coatedsilicon carbon composite, wherein the pellet density ranges from 1.0 to1.5 g/cm³, the skeletal density as measured by helium pycnometry rangesfrom 1.5 to 1.6 g/cm³, the skeletal volume as measured by heliumpycnometry ranges from 0.625 to 0.666 cm³/g, and thenitrogen-inaccessible volume ranges from 0.05 to 0.1 cm³/g.Alternatively, the above elements are combined with anitrogen-inaccessible volume ranging from 0.05 to 0.5 cm³/g, or 0.2 to0.4 cm³/g, or 0.1 to 0.3 cm³/g, or 0.3 to 0.5 cm³/g.

Example 34 Observed Capacity Loss for Silicon within the Silicon CarbonComposite after Various Coating Techniques

A mixed micro- and mesoporous carbon scaffold was employed to produce asilicon carbon composite in the presence of silane as generallydescribed herein. Said silicon carbon composite particles were furthercarbon coated employing two methods: CVD with carbon containing gas(specifically methane and acetylene), and coating with conductivepolymer, wherein said polymer is optionally partially pyrolyzed.

As described elsewhere in this disclosure, the silicon carbon compositeparticle can be coating employing a conductive polymer. In certainembodiments, the conductive polymer is pyrolyzed to achieve a pyrolyzedconductive polymer coating. There are various embodiments whereby theconductive polymer can be added as a second carbon composite with thesilicon carbon composite. For example, the silicon-carbon composite canbe suspended in a solvent containing dissolved conductive polymer, thesuspension can then be dried as known in the art. In an alternateembodiment, solid particles of conductive polymer can be mixed withsolid silicon particles, and the mixture of particles stored at elevatedtemperature. In preferred embodiments, the temperature is near or abovethe glass transition temperature of the polymer. In additional preferredembodiments, the temperature is near or above the softening temperatureof the polymer. In additional preferred embodiments, the temperature isnear or above the melting temperature of the polymer. The elevatedtemperature may be about 100° C., or about 120° C., or about 140° C., orabout 160° C., or about 180° C., or about 200° C. The pyrolysis can beconducted at elevated temperature as known in the art, for example at300° C., or 350° C., or 400° C., or 450° C., or 500° C., or 600° C., or700° C., or 800° C. In some embodiments, the pyrolysis can be conductedat 850° C., 900° C., 1000° C., 1050° C., or 1100° C. Exemplaryconductive polymers include, but are not limited to, polyacrylonitrile(PAN), polyaniline, polypyrrole, polyacetylene, polyphenylene,polyphenylene sulfide, polythiophene, poly(fluorene)s, polypyrenes,polyazulenes, polynaphthalenes, polycarbazoles, polyindoles,polyazepines, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(p-phenylenesulfide) (PPS), poly(p-phenylene vinylene) (PPV), and mixtures thereof.The ratio of nano-featured or nano-featured and nano-sized silicon toconductive polymer can be varied, for example, from 95:5 to 9:95. Incertain embodiments, the ratio of silicon to conductive polymer is 95:5to 60:40, or 90:10 to 70:30.

For the current example, Table 27 presents a comparison of the measuredcapacity and calculated silicon capacity (in half cells) for thevariously carbon coated silicon composites. Sample 34-1 was acarbon-coated silicon carbon composite achieved by mixing 9:1 w:wcomposite:PAN and heating to 400° C. for 60 min. Sample 34-2 was acarbon-coated silicon carbon composite achieved by mixing 7:3 w:wcomposite:PAN and heating to 400° C. for 60 min. Sample 34-3 was acarbon-coated silicon carbon composite achieved by mixing 9:1 w:wcomposite:PAN and heating to 300° C. for 60 min. Sample 34-4 was acarbon-coated silicon carbon composite that achieved by heating thesilicon carbon composite to 800° C. for 60 min in the presence ofpropane. Sample 34-5 was a carbon-coated silicon carbon composite thatachieved by heating the silicon carbon composite to 980° C. for 15 minin the presence of methane. Sample 34-6 was a carbon-coated siliconcarbon composite that achieved by heating the silicon carbon compositeto 550° C. for 15 min in the presence of acetylene. The followingassumption were employed: the yield for PAN at 400° C. and 300° C. was84% and 98% respectively, and the capacity of PAN in half cells over thevoltage window tested was the same as the carbon comprising thescaffold, namely 360 mAh/g.

TABLE 27 Sample and pore volumes according to Example 32. CapacityWeight Final Expected % of Sample Capacity Change After Gain AfterCoating Capacity Expected Description (mAh/g) Coating (%) Coating (%)(%) (mAh/g) Capacity 34-1 1677 95.88%  9% 8.5% 1632 103% 34-2 118478.83% 36% 26.5% 1199  99% 34-3 1301 98.19% 11% 9.7% 1231 106% 34-4 116077.23%  2% 2.0% 1306  89% 34-5 1061 80.08% 16% 13.8% 1192  89% 34-6 132399.85% 4.6%  4.4% 1283 103%

As can be seen, the carbon coating achieved via CVD at high temperature(at or above 800° C.) generally resulted in decreased silicon in thecarbon coated silicon composite compared to the non-coated siliconcomposite. When the CVD was applied at relatively low temperature, forexample at 550° C., there was no capacity loss. For the examples werecarbon coating was achieved employing a conductive polymer, the processcan be carried at lower temperatures, below 550° C. and even as low at300° C., there was no loss of silicon capacity in the carbon coatedsilicon composite compared to the non-coated silicon composite.

Example 35 Full Cell Electrochemical Performance of C-Coated SiliconCarbon Composite Wherein the Carbon Coating was Achieved by Coating withConductive Polymer

Carbon scaffold material comprising a mixed micro- and mesoporous naturewas processed into silicon carbon composite employing asilicon-containing reactant. All processing was conducted as generallydescribed elsewhere in this disclosure. This sample (denoted non-carboncoated or non C-coated) was tested electrochemically in full cells asgenerally described within this disclosure. For comparison, the samesilicon carbon scaffold was subject to an addition process of carboncoating by heating a mixture of 9:1 (w:w) composite:PAN to 500° C. for60 min. This latter sample (denoted carbon-coated or C-coated) was alsotested electrochemically in full cells as generally described withinthis disclosure.

The cycle life data for the full cells are presented in FIG. 22. For theC-coated sample, the cycling rate was 1 C. For the non C-coated sample,the cycling rate was 1 C. As can be seen, there was a much greaterstability for the C-coated silicon carbon composite. Without being boundby theory, the additional carbon coating enveloping the silicon-carboncomposite particle allows for reducing particle expansion and providingmore favorable SEI. Accordingly, the silicon carbon composite particlecomprises a terminal coating of carbon, wherein said carbon comprisespartially pyrolyzed conductive polymer, and wherein said terminalcoating represents 0.1 to 30% of the total mass of the silicon carboncomposite particle, for example 2-30% of the total mass of the siliconcarbon composite particle, for example 5-25% of the silicon carboncomposite particle, for example 10-20% of the silicon carbon compositeparticle. Alternatively, the carbon coating comprising partiallypyrolyzed conductive polymer represents 1-10% of the silicon carboncomposite particle, for example 5-10% of the silicon carbon compositeparticle. Alternatively, the carbon coating comprising partiallypyrolyzed conductive polymer represents 10-30% of the silicon carboncomposite particle, for example 20-30% of the silicon carbon compositeparticle.

Example 36 Full Cell Electrochemical Performance of C-Coated SiliconCarbon Composite Compared to Graphite

Carbon scaffold material comprising a mixed micro- and mesoporous naturewas processed into a carbon-coated silicon carbon composite generallyaccording to the procedures described herein. The carbon scaffoldcomprised a Dv,50 of 4 um and a mixed micro- and mesoporous nature, andthe silicon carbon composite was produced employing a silicon-containingreactant consistent with methodologies described within this disclosure,and the terminal carbon coating was achieved employing CVD consistentwith methodologies described within this disclosure. The carbon-coatedsilicon carbon composite was tested for electrochemical performance in afull cell, pouch cell format. The anode comprised the carbon-coatedsilicon carbon composite blended graphite to achieve a target of 650mAh/g (on an anode active basis), binder, and conductivity enhancer. Theanode cross-sectional capacity was 1.9 mAh/cm². The cathode comprisedNCA. The cycling was accomplished at a rate of C/2. The voltage windowwas 2.0 to 4.2 V with an 1/20 hold. The electrolyte comprised 1 M LiPF₆EC:DEC+10% FEC. For comparison, a comparator full cell, pouch cell wasalso tested electrochemical under the same conditions as described abovefor the carbon-coated silicon carbon composite. The cathodecross-sectional capacity was 1.6 mAh/cm².

The full cell data are presented in FIG. 23. As can be seen, the anodecomprising the carbon-coated silicon composite exhibited a gravimetriccapacity based on total mass of anode and cathode that was higher thanthe graphite anode, and maintained superiority over the graphite anodefor over 400 cycles. According, the present invention allows for ananode comprising a carbon-coated silicon carbon composite with agravimetric capacity based on total mass of anode and cathode greaterthan graphite's gravimetric capacity based on total mass of anode andcathode for at least 400 cycles. According, the present invention allowsfor an anode comprising a carbon-coated silicon carbon composite with agravimetric capacity based on total mass of anode and cathode greaterthan graphite's gravimetric capacity based on total mass of anode andcathode for at least 500 cycles. According, the present invention allowsfor an anode comprising a carbon-coated silicon carbon composite with agravimetric capacity based on total mass of anode and cathode greaterthan graphite's gravimetric capacity based on total mass of anode andcathode for at least 600 cycles. According, the present invention allowsfor an anode comprising a carbon-coated silicon carbon composite with agravimetric capacity based on total mass of anode and cathode greaterthan graphite's gravimetric capacity based on total mass of anode andcathode for at least 800 cycles. According, the present invention allowsfor an anode comprising a carbon-coated silicon carbon composite with agravimetric capacity based on total mass of anode and cathode greaterthan graphite's gravimetric capacity based on total mass of anode andcathode for at least 1000 cycles. According, the present inventionallows for an anode comprising a carbon-coated silicon carbon compositewith a gravimetric capacity based on total mass of anode and cathodegreater than graphite's gravimetric capacity based on total mass ofanode and cathode for at least 2000 cycles.

In some various different embodiments, the anode cross-sectionalcapacity is at least 1.7 mAh/cm², at least 1.8 mAh/cm², at least 1.9mAh/cm², at least 2.0 mAh/cm², at least 2.1 mAh/cm², at least 2.2mAh/cm² or at least 2.3 mAh/cm².

Example 37 Full Cell Electrochemical Performance of C-Coated SiliconCarbon Composite in Three-Electrode Pouch Cell

Carbon scaffold material comprising a mixed micro- and mesoporous naturewas processed into a carbon-coated silicon carbon composite generallyaccording to the procedures described herein. The carbon scaffoldcomprised a Dv,50 of 4 um and a mixed micro- and mesoporous nature, andthe silicon carbon composite was produced employing a silicon-containingreactant consistent with methodologies described within this disclosure,and the terminal carbon coating was achieved employing CVD consistentwith methodologies described within this disclosure. The carbon-coatedsilicon carbon composite was tested for electrochemical performance in afull cell, three-electrode pouch cell format. The anode comprised thecarbon-coated silicon carbon composite blended graphite to achieve atarget of 650 mAh/g (on an anode active basis), binder, and conductivityenhancer. The anode was NCA, and a third electrode comprised of lithiumwas also employed. Such a three-electrode system is known in the art asa useful tool to independently track performance of anode and cathode.For the purpose of the current example, the stability of anode andcathode were monitored for their differential voltage curves vs cycle.As known in the art, the differential voltage curve, that is, the plotof the first derivative of voltage vs. the voltage can be monitored, andthe change in said different voltage curve over cycling can be monitoredto independently assess the stability of anode and cathode. The changein differential voltage over time for the anode and cathode are depictedin FIG. 24 and FIG. 25, respectively.

As can be seen, the change in different voltage curve for the cathodedeteriorates much faster compared to the differential voltage curve forthe anode comprising the carbon-coated silicon carbon composite.Accordingly, the stability of the carbon-coated silicon carbon compositeis superior to the cathode employed. Consequently, the current abilityto determine the full stability potential for the carbon-coated siliconcarbon composite is limited by the stability of the cathode and othercell level considerations. Accordingly, it is anticipated that furtherimprovements regarding the cathode and cell level improvements willremove such constraints and commensurately greater stability for theanode comprising the carbon-coated silicon carbon composite will beobtained.

Example 38 Production of Silicon Carbon Composites from Catalyst-DopedPorous Carbon Materials

In certain embodiments the porous carbon scaffold is doped with one ormore catalysts. The presence of a catalyst within the porous carbonfacilitated the subsequent production of the silicon carbon composite.Without being bound by theory, the presence of catalyst(s) within thepores of the porous carbon provides a site for the silicon-containingreactant, for example the silicon-containing gas, for example silane, todeposit and decompose into the silicon portion of the silicon carboncomposite. Importantly, the presence of catalyst(s) within the porouscarbon allows for preferential deposition of silicon within the pores ofthe carbon, as opposed to the outside surface of the carbon particle, oroutside the carbon particle itself (for example, on hot reactor walls orother non-carbon surfaces within the compositing reactor). Methods forproducing catalyst-doped porous carbon are known in the art, and includeadmixing of carbon and catalyst, suspension of carbon particles in asolution of catalyst followed by collection of carbon particles anddrying, and incorporation of catalyst within the polymer resin fromwhich the porous carbon was produced. Suitable catalysts in this regardinclude, but are not limited to, nickel, copper, iron, manganese, gold,aluminum, tin, palladium, platinum ruthenium, rhodium, iridium, andcombinations thereof. Without being bound by theory, in the case of ametal catalyst, this catalytic effect can proceed via an alloyingeutectic reaction as in the case of aluminum, nickel and gold or ahydrogenation effect (such as platinum or nickel) wherein the Si—H bondis more easily cleaved on the metal surface. Suitable precursors for theabove catalysts include their salts and other oxidized forms such astheir corresponding oxides, halide salts, nitrates, carbonate,carboxylates, sulfates, and the like, and combinations thereof. Thelevel of catalyst within the porous carbon scaffold can be varied, forexample from 0.1 to 20%, for example from 0.5% to 10%, for example from1% to 5%, for example from 1% to 4%. In some embodiments, the catalystcan be removed after the production of the silicon carbon composite, forexample by dissolution in media that dissolved the catalyst, but doesnot dissolve carbon and does not dissolve silicon.

In a certain embodiment the catalyst-doped porous carbon scaffolds wereprepared by suspending carbon particles in aqueous solutions of variousmetal acetate salts to achieve a target catalyst loading of ˜2 wt %after subsequent reduction of the metal catalyst and subsequent silicondeposition using 1.25 mol % SiH₄/N₂ gas at a reduced temperature of 430°C. (vs. standard temp of 450° C.) for 2.5 h. The porous carbon employedcomprised a mixed micro- and mesoporous structure and a Dv,50 ofapproximately 20 um. The data for the carbon scaffolds and the resultingsilicon carbon scaffolds are presented in Table 28.

As can be seen, the porous scaffolds that were treated with the catalystexhibited a reduced pore volume, indicating the catalyst indeeddeposited within the porosity of the carbon scaffold. Also as can beseen, all of the silicon carbon composites produced from catalyst-dopedporous carbon scaffolds exhibited lower surface area and pore volumecompared to the starting, non-catalyst-doped carbon scaffold. These dataindicated the utility of the catalyst in promoting the deposition ofsilicon from decomposition of the silane gas. Also, there was a trendfor higher silicon loading for the catalyst-doped silicon carbonscaffold, particularly for when the catalyst was nickel or manganese.The silicon carbon composite produced from the nickel-doped porouscarbon was tested electrochemically in a lithium ion half cell asgenerally described herein. The silicon carbon composite produced fromthe nickel-doped porous carbon exhibited a first cycle efficiency of72%, a maximum gravimetric capacity of 1362 mAh/g, and an averageCoulombic efficiency of 99.85%, and a capacity retention of 93% at cycle20. This electrochemical performance demonstrates the utility of theconcept of catalyst doping of the porous carbon towards improvingutility, scalability, performance, cost or other aspects of the currentinvention that can be reduced to practice.

TABLE 28 Physicochemical data for various porous carbons and siliconcarbon composites according to Example 38. Surface Total Pore AreaVolume TGA Weight Sample Description (m²/g) (cm³/g) % SiliconNon-catalyst doped carbon 654 0.610 Not applicable scaffold Siliconcarbon composite Not measured 6% made from Non-catalyst doped carbonscaffold Ni-doped carbon scaffold 672 0.645 Not applicable Cu-dopedcarbon scaffold 667 0.630 Not applicable Mn-doped carbon scaffold 6900.655 Not applicable Fe- doped carbon scaffold 682 0.659 Not applicableSilicon carbon composite 340 0.313 22%  produced from Ni-doped carbonscaffold Silicon carbon composite 543 0.523 7% produced from Cu-dopedcarbon scaffold Silicon carbon composite 399 0.378 17%  produced fromMn-doped carbon scaffold Silicon carbon composite 562 0.539 6% producedfrom Fe- doped carbon scaffold

Example 39 Particle Expansion for Silicon Carbon Composites Measured byTem of the Lithiated Particle

Within this disclosure the surprising and unexpected low expansion ofthe novel silicon carbon composites has been described, for example forlithiated anodes comprising the silicon carbon composite. Theseapproaches, while highly useful, are carried out on an electrode, i.e.,anode, basis. For the current example, we have employed a techniqueknown in the art suitable for monitoring the expansion of materials atthe resolution of their individual particles. Specifically, in-situ TEMwas conducted. This procedure has been previously described in the art,and details of the procedure can be found elsewhere (Gu, M.; Wang, Z.;Connell, J. G.; Perea, D. E.; Lauhon, L. J.; Gao, F.; Wang, C. ACS Nano2013, 7, 6303-6309).

The data are presented in FIG. 26 for the case of a silicon carboncomposite and in FIG. 27 for a carbon-coated silicon carbon composite.The carbon scaffold employed for this example comprised a Dv,50 of 4 umand a mixed micro- and mesoporous nature, and the silicon carboncomposite was produced employing a silicon-containing reactantconsistent with methodologies described within this disclosure, and theterminal carbon coating was achieved employing CVD consistent withmethodologies described within this disclosure. For the purpose of thecurrent example, the expansion reported in the particle expansion, inparticular the particle expansion as recorded is 2-dimensions, that isthe exact visualization of the expansion observed for the in-situ TEMtechnique employed. As can be seen, the expansion was only 42% for thesilicon carbon composite, and only 29% for the carbon-coated siliconcarbon composite. The data for the average particle expansion observedfor the various composites is presented in Table 29.

TABLE 29 Average particle expansion for various silicon carboncomposites according to Example 39. Average particle Sample andDescription expansion (%) Non carbon coated silicon carbon composite 42%according to Sample 28-1 Carbon coated silicon carbon composite 33%according to Sample 28-1 Carbon coated silicon carbon composite 22%according to Sample 25-13A Carbon coated silicon carbon composite 97%according to Sample 27-2 Carbon coated silicon carbon composite 39%according to Sample 25-6A

Accordingly, embodiments of the current invention allow for a novelcomposition of matter comprising silicon carbon composite particles,wherein the particle expansion upon lithiation is 10-100% as determinedby in-situ TEM. In certain embodiments, the silicon carbon compositeparticle expansion upon lithiation is 10-50% as determined by in-situTEM. In certain embodiments, the silicon carbon composite particleexpansion upon lithiation is 10-40% as determined by in-situ TEM. Incertain embodiments, the silicon carbon composite particle expansionupon lithiation is 10-30% as determined by in-situ TEM. In certainembodiments, the silicon carbon composite particle expansion uponlithiation is 20-30% as determined by in-situ TEM.

The silicon carbon composites were also examined by ex-situ TEM. Thedata revealed the presence of silicon primary particles that weresubstantially sub-micron, for example 50 nm or less, for example 40 nmor less, for example 20 nm. This method also allowed for determinationof crystallinity of the silicon by analysis of the electron beamdiffraction. The data indicated that the silicon had a poly-crystallinenature.

Exemplary embodiments include, but are not limited to, the following:

Embodiment 1

A composite comprising a porous carbon scaffold and silicon, wherein thecomposite comprises from 15 to 85% silicon by weight and anitrogen-inaccessible volume ranging from 0.05 to 0.5 cm³/g, and whereinthe composite comprises a plurality of particles having a particleskeletal density ranging from 1.5 to 2.2 g/cm³, as measured by heliumpycnometry.

Embodiment 2

The composite of embodiment 1, wherein the nitrogen-inaccessible volumeranges from 0.2 to 0.4 cm³/g.

Embodiment 3

The composite of embodiment 1, wherein the nitrogen-inaccessible volumeranges from 0.1 to 0.3 cm³/g.

Embodiment 4

The composite of any one of embodiments 1-3, wherein the skeletaldensity ranges from 1.9 to 2.2 g/cm³.

Embodiment 5

The composite of any one of embodiments 1-3, wherein the skeletaldensity ranges from 1.5 to 1.8 g/cm³.

Embodiment 6

The composite of any one of embodiments 1-5, having a pellet densityranging from 1.0 to 1.5 g/cm³.

Embodiment 7

The composite of any one of embodiments 1-6, wherein the composite has apore structure comprising less than 10% micropores, greater than 30%mesopores, greater than 30% macropores and a total pore volume less than0.1 cm³/g, as determined by nitrogen sorption.

Embodiment 8

The composite of any one of embodiments 1-6, wherein the composite has apore structure comprising 30-60%% micropores 30-60%% mesoporesless than10% macropores and a total pore volume less than 0.1 cm³/g, asdetermined by nitrogen sorption.

Embodiment 9

The composite of any one of embodiments 1-6, wherein the composite has apore structure comprising less than 20% micropores, greater than 60%mesopores, less than 30% macropores and a total pore volume less than0.1 cm³/g, as determined by nitrogen sorption.

Embodiment 10

The composite of any one of embodiments 1-6, wherein the porous carbonscaffold has a pore structure comprising 30-60% micropores, 30-60%mesopores, less than 10% macropores and a total pore volume between 0.1and 0.5 cm³/g, as determined by nitrogen sorption.

Embodiment 11

The composite of any one of embodiments 1-6, wherein the porous carbonscaffold has a pore structure comprising 40-60% micropores, 40-60%mesopores, less than 1% macropores and a total pore volume between 0.1and 0.5 cm³/g, as determined by nitrogen sorption.

Embodiment 12

The composite of any one of embodiments 1-11, wherein the particleskeletal density ranges from 1.5 to 1.8 g/cm³.

Embodiment 13

The composite of any one of embodiments 1-6, wherein the porous carbonscaffold comprises 10-50% of pores having a diameter from 50-200 A andgreater than 90% of pores having a diameter less than 200 A.

Embodiment 14

The composite of any one of embodiments 1-13, wherein the siliconcontent ranges from 25% to 65%.

Embodiment 15

The composite of any one of embodiments 1-13, wherein the siliconcontent ranges from 35% to 45%.

Embodiment 16

The composite of any one of embodiments 1-15, having a ratio of porevolume of the carbon scaffold to silicon volume between 0.3:1 and 1:1,between 0.4:1 and 1:1, between 0.4:1 and 1:1, between 0.5:1 and 1:1,between 0.6:1 and 1:1, between 0.3:1 and 0.9:1, between 0.3:1 and 0.8:1or between 0.3:1 and 0.7:1.

Embodiment 17

The composite of any one of embodiments 1-15, having a ratio ofnitrogen-inaccessible pore volume to silicon volume between 0.3:1 and1:1.

Embodiment 18

The composite of any one of embodiments 1-17, wherein the averageparticle size less than 5 microns.

Embodiment 19

The composite of embodiment 18, wherein the average particle size lessthan 1 micron.

Embodiment 20

The composite of any one of embodiments 1-19, comprising a plurality ofparticles, wherein each particle comprises a surface layer of carbon.

Embodiment 21

The composite of embodiment 20, wherein the surface layer of carboncomprises from 1 to 20% of the total mass of the particle.

Embodiment 22

The composite of embodiment 20, wherein the surface layer of carboncomprises from 2 to 10% of the total mass of the particle.

Embodiment 23

The composite of any one of embodiments 20-22, wherein the surface layerof carbon comprises a pyrolyzed or partially pyrolyzed conductivepolymer.

Embodiment 24

The composite of embodiment 23, wherein the conductive polymer comprisespolyacrylonitrile or poly(3,4-ethylenedioxythiophene).

Embodiment 25

The composite of any one of embodiments 20-22, wherein the surface layerof carbon comprises a graphitizable carbon.

Embodiment 26

The composite of any one of embodiments 1-25, further comprising ametal.

Embodiment 27

The composite of embodiment 26, wherein the metal is aluminum, nickel ormanganese.

Embodiment 28

The composite of any one of embodiments 1-27, wherein particles ofcomposite have an average expansion upon litiation ranging from 10 to100% as determined by in situ TEM.

Embodiment 29

The composite of embodiment 28, wherein the average expansion rangesfrom 10 to 50%.

Embodiment 30

The composite of embodiment 29, wherein the average expansion rangesfrom 20 to 30%.

Embodiment 31

The composite of any one of embodiments 1-30, wherein the compositecomprises a plurality of particles, the particles having an averagediameter less than 50 nm as determined by ex-situ TEM.

Embodiment 32

An electrode comprising a composite according to any one of embodiments1-31.

Embodiment 33

The electrode of embodiment 32, wherein the electrode is an anode.

Embodiment 34

An energy storage device comprising a composite material according toany one of embodiments 1-31 or an electrode according to any one ofembodiments 32 or 33.

Embodiment 35

The energy storage device of embodiment 34, wherein the device is alithium ion battery.

Embodiment 36

An electrode comprising a carbon-silicon composite, wherein theelectrode comprises a volumetric capacity at full lithiation rangingfrom 250 to 350 mAh/cm³ and an expansion of less than 40%.

Embodiment 37

The electrode of embodiment 36, having an expansion of less than 30%.

Embodiment 38

An electrode comprising a carbon-silicon composite, wherein theelectrode comprises a volumetric capacity at full lithiation rangingfrom 350 to 450 mAh/cm³ and an expansion of less than 60%.

Embodiment 39

The electrode of embodiment 38, having an expansion of less than 40%.

Embodiment 40

An electrode comprising a carbon-silicon composite, wherein theelectrode comprises a volumetric capacity at full lithiation rangingfrom 450 to 600 mAh/cm³ and an expansion of less than 100%.

Embodiment 41

The electrode of embodiment 40, having an expansion of less than 80%.

Embodiment 42

An electrode comprising a carbon-silicon composite, wherein theelectrode comprises a capacity retention of greater than 100% for atleast 100 charge and discharge cycles.

Embodiment 43

An electrode comprising a carbon-silicon composite, wherein the anodecomprises a gravimetric capacity of greater than 400 mAh/g, based onmass of the anode electrode, for at least 500 charge and dischargecycles when tested in a lithium ion full cell, wherein the anode is notpre-lithiated, and wherein the full cell comprises an cathode comprisingLiNi_(0.8)CO_(0.15)Al_(0.05)O₂ present at a anode:cathode capacity ratioof 1.05 to 1.15, and an electrolyte comprising 1 M LiPF6 in 2:1 (w:w)ethylene carbonate:diethyl carbonate solvent with 10% (w/w)fluoroethylene carbonate, and wherein the full cell is tested at 25 Cover a voltage of 4.2 to 2.5 V at a symmetric charge-discharge currentdensity equivalent to C/10 for the first cycle, followed by a symmetriccharge-discharge current density equivalent 1 C for 20 cycles with asymmetric charge-discharge current density equivalent to C/10 cycleevery 20^(th) subsequent cycle, and wherein after each charge thevoltage is held at 4.2 V until the current reaches half of the symmetriccharging current.

Embodiment 44

An electrode comprising a carbon-silicon composite, wherein theelectrode comprises a gravimetric capacity of greater than 600 mAh/g,based on mass of the electrode, for at least 500 charge and dischargecycles.

Embodiment 45

An electrode comprising a carbon-silicon composite, wherein theelectrode comprises a gravimetric capacity of greater than 400 mAh/gwhen tested in a half cell at a 2 C cycling rate.

Embodiment 46

The electrode of embodiment 45, wherein the gravimetric capacity isgreater than 600 mAh/g.

Embodiment 47

The electrode of embodiment 45, wherein the gravimetric capacity isgreater than 800 mAh/g.

Embodiment 48

The electrode of any one of embodiments 45-47, wherein the gravimetriccapacity decreases by no more than 80% after 100 or more charge anddischarge cycles.

Embodiment 49

An electrode comprising a carbon-silicon composite, wherein theelectrode comprises a density of at least 1.2 g/cm³, and a gravimetriccapacity of greater than 400 mAh/g for at least 500 charge and dischargecycles.

Embodiment 50

The electrode of embodiment 49, wherein the density is at least 1.3g/cm³.

Embodiment 51

The electrode of embodiment 49, wherein the density is at least 1.4g/cm³.

Embodiment 52

The electrode of embodiment 49, wherein the density is at least 1.5g/cm³.

Embodiment 53

An electrode comprising a carbon-silicon composite, wherein theelectrode comprises a gravimetric capacity, based on total mass of theelectrode, greater than the gravimetric capacity of a correspondinggraphite electrode, based on total mass of the graphite electrode, forat least 400 charge and discharge cycles.

Embodiment 54

An electrode comprising a carbon-silicon composite, wherein theelectrode comprises an expansion upon lithiation ranging from 10-100% asdetermined by in-situ TEM.

Embodiment 55

The electrode of embodiment 54, wherein the expansion ranges from10-50%.

Embodiment 56

The electrode of embodiment 54, wherein the expansion ranges from20-30%.

Embodiment 57

The electrode of any one of embodiments 36-56, wherein the electrode isan anode.

Embodiment 58

The electrode of any one of embodiments 36-57, wherein thecarbon-silicon composite comprises the composite of any one ofembodiments 1-31.

Embodiment 59

The electrode of any one of embodiments 36-58, wherein the electrodecomprises an electronically and/or ionically conductive binder.

Embodiment 60

The electrode of embodiment 59, wherein the binder is a conductivepolymer or partially pyrolyzed form thereof.

Embodiment 61

A carbon material having a surface area of 100 to 2000 m²/g and a totalpore volume, wherein less than 10% of the pore volume resides inmicropores greater than 80% of the pore volume resides in mesoporesvolume and less than 5% of the pore volume resides in macropores.

Embodiment 62

The carbon material of embodiment 61, wherein greater than 90% of thepore volume resides in mesopores.

Embodiment 63

The carbon material of any one of embodiments 61 or 62, wherein lessthan 5% of the pore volume resides in micropores.

Embodiment 64

The carbon material of any one of embodiments 61-63, wherein less than5% of the pore volume resides in macropores.

Embodiment 65

The carbon material of any one of embodiments 61-64, having a surfacearea of 100 to 1000 m²/g.

Embodiment 66

The carbon material of any one of embodiments 61-64, having a surfacearea of 100 to 500 m²/g.

Embodiment 67

A method for producing a composite a material comprising a porousscaffold material and silicon comprising the following steps:

a) creation of a porous scaffold material, wherein the said porousscaffold material comprises 10-50% of pores having a diameter from50-200 A and greater than 90% of pores having a diameter less than 200A; and

b) impregnation of silicon within the porous scaffold material,resulting in a silicon-impregnated scaffold material.

Embodiment 68

A method for producing a composite material comprising a porous carbonscaffold and silicon comprising the following steps:

a. mixing polymer precursors materials and storing for a period of timeat sufficient temperature to allow for polymerization of the precursors;

b. carbonization of the resulting polymer material to create a porouscarbon material comprising 10-50% of pores having a diameter from 50-200A and greater than 90% of pores having a diameter less than 200 A; and

c. subjecting the porous carbon material to elevated temperature in thepresence of a silicon-containing gas, resulting in a silicon-impregnatedcarbon material.

Embodiment 69

A method for producing a composite material comprising a porous carbonscaffold and silicon comprising the following steps:

a) mixing polymer precursors materials and storing for a period of timeat sufficient temperature to allow for polymerization of the precursors;

b) carbonization of the resulting polymer material to create a porouscarbon material comprising 10-50% of pores having a diameter from 50-200A and greater than 90% of pores having a diameter less than 200 A;

c) subjecting the porous carbon material to elevated temperature in thepresence of a silicon-containing gas, resulting in a silicon-impregnatedcarbon material; and

d) applying a carbon layer on the silicon-impregnated carbon material toyield a carbon-coated, silicon-impregnated carbon material

Embodiment 70

A method for producing a composite material comprising a porous carbonscaffold and silicon comprising the following steps:

a) mixing polymer precursors materials and storing for a period of timeat sufficient temperature to allow for polymerization of the precursors;

b) carbonization of the resulting polymer material to create a porouscarbon material comprising 10-50% of pores having a diameter from 50-200A and greater than 90% of pores having a diameter less than 200 A;

c) subjecting the porous carbon material to elevated temperature in thepresence of a silicon-containing gas, resulting in a silicon-impregnatedcarbon material; and

d) applying conductive polymer around the silicon-impregnated carbonmaterial to yield a silicon-impregnated carbon material further embeddedwithin a conductive polymer network.

Embodiment 71

A method for producing a composite material comprising a porous carbonscaffold and silicon comprising the following steps:

a) mixing polymer precursors materials and storing for a period of timeat sufficient temperature to allow for polymerization of the precursors;

b) carbonization of the resulting polymer material to create a porouscarbon material comprising 10-50% of pores having a diameter from 50-200A and greater than 90% of pores having a diameter less than 200 A;

c) subjecting the porous carbon material to elevated temperature in thepresence of a silicon-containing gas, resulting in a silicon-impregnatedcarbon material;

d) applying a carbon layer on the silicon-impregnated carbon material toyield a carbon-coated, silicon-impregnated carbon material; and

e) applying conductive polymer around the carbon-coated,silicon-impregnated carbon material to yield a carbon-coated,silicon-impregnated carbon material further embedded within a conductivepolymer network.

Embodiment 72

The method of any one of embodiments 67-71 wherein the deposition ofsilicon is accomplished by processing in a reactor at a temperaturebetween 300 and 600° C. in the presence of a silicon-containing gas.

Embodiment 73

The method of embodiment 72, wherein the silicon-containing gas and thereactor is a tube furnace, fluid bed reactor, rotary kiln reactor,elevator kiln, or roller hearth kiln.

Embodiment 74

The method of embodiment 72, wherein the silicon-containing gas issilane, dichlorosilane, trichlorosilane, tetrachlorosilane.

Embodiment 75

The method of embodiment 72, wherein the silicon-containing gas issilane.

Embodiment 76

The method of embodiment 69 or embodiment 71, wherein the carbon layeraccording to step (d) is accomplished by chemical vapor deposition in areactor in the presence of an organic gas and elevated temperature.

Embodiment 77

The method of embodiment 76 wherein the organic gas is methane, ethane,propane, or butane and the temperature is between 500 and 900° C.

Embodiment 78

The method of embodiment 77, wherein the organic gas is propane and thetemperature is between 750 and 850° C.

Embodiment 79

The method of any one of embodiments 67-78, further comprisingcontacting the porous carbon material or porous scaffold with a catalystprior to preparation of the silicon-impregnated scaffold material orsilicon-impregnated carbon material.

Embodiment 80

The method of embodiment 79, wherein the catalyst is a metal.

Embodiment 81

The method of embodiment 80, wherein the metal is aluminum, nickel ormanganese.

Embodiment 82

The method of any one of embodiments 67-81, wherein the compositematerial is a composite according to any one of embodiments 1-31.

1. A composite comprising a porous carbon scaffold and silicon, whereinthe composite comprises from 15 to 85% silicon by weight and anitrogen-inaccessible volume ranging from 0.05 to 0.5 cm³/g, and whereinthe composite comprises a plurality of particles having a particleskeletal density ranging from 1.5 to 2.2 g/cm³, as measured by heliumpycnometry.
 2. The composite of claim 1, wherein thenitrogen-inaccessible volume ranges from 0.2 to 0.4 cm³/g.
 3. Thecomposite of claim 1, wherein the nitrogen-inaccessible volume rangesfrom 0.1 to 0.3 cm³/g.
 4. The composite of claim 1, wherein the skeletaldensity ranges from 1.9 to 2.2 g/cm³.
 5. The composite of claim 1,wherein the skeletal density ranges from 1.5 to 1.8 g/cm³.
 6. Thecomposite of claim 1, having a pellet density ranging from 1.0 to 1.5g/cm³.
 7. The composite of claim 1, wherein the composite has a porestructure comprising less than 10% micropores, greater than 30%mesopores, greater than 30% macropores and a total pore volume less than0.1 cm³/g, as determined by nitrogen sorption.
 8. The composite of claim1, wherein the composite has a pore structure comprising 30-60%%micropores 30-60%% mesoporesless than 10% macropores and a total porevolume less than 0.1 cm³/g, as determined by nitrogen sorption.
 9. Thecomposite of claim 1, wherein the composite has a pore structurecomprising less than 20% micropores, greater than 60% mesopores, lessthan 30% macropores and a total pore volume less than 0.1 cm³/g, asdetermined by nitrogen sorption.
 10. The composite of claim 1, whereinthe porous carbon scaffold has a pore structure comprising 30-60%micropores, 30-60% mesopores, less than 10% macropores and a total porevolume between 0.1 and 0.5 cm³/g, as determined by nitrogen sorption.11. The composite of claim 1, wherein the porous carbon scaffold has apore structure comprising 40-60% micropores, 40-60% mesopores, less than1% macropores and a total pore volume between 0.1 and 0.5 cm³/g, asdetermined by nitrogen sorption.
 12. The composite of claim 1, whereinthe particle skeletal density ranges from 1.5 to 1.8 g/cm³.
 13. Thecomposite of claim 1, wherein the porous carbon scaffold comprises10-50% of pores having a diameter from 50-200 A and greater than 90% ofpores having a diameter less than 200 A.
 14. The composite of claim 1,wherein the silicon content ranges from 25% to 65%.
 15. (canceled) 16.The composite of claim 1, having a ratio of pore volume of the carbonscaffold to silicon volume between 0.3:1 and 1:1.
 17. The composite ofclaim 1, having a ratio of nitrogen-inaccessible pore volume to siliconvolume between 0.3:1 and 1:1.
 18. The composite of claim 1, wherein theaverage particle size less than 5 microns.
 19. (canceled)
 20. Thecomposite of claim 1, comprising a plurality of particles, wherein eachparticle comprises a surface layer of carbon.
 21. The composite of claim20, wherein the surface layer of carbon comprises from 1 to 20% of thetotal mass of the particle.
 22. (canceled)
 23. The composite of claim20, wherein the surface layer of carbon comprises a pyrolyzed orpartially pyrolyzed conductive polymer.
 24. The composite of claim 23,wherein the conductive polymer comprises polyacrylonitrile orpoly(3,4-ethylenedioxythiophene).
 25. The composite of claim 20, whereinthe surface layer of carbon comprises a graphitizable carbon.
 26. Thecomposite of claim 1, further comprising a metal.
 27. The composite ofclaim 26, wherein the metal is aluminum, nickel or manganese.
 28. Thecomposite of claim 1, wherein particles of composite have an averageexpansion upon litiation ranging from 10 to 100% as determined by insitu TEM.
 29. The composite of claim 28, wherein the average expansionranges from 10 to 50%.
 30. (canceled)
 31. The composite of claim 1,wherein the composite comprises a plurality of particles, the particleshaving an average diameter less than 50 nm as determined by ex-situ TEM.32. An electrode comprising a composite according to claim
 1. 33.(canceled)
 34. An energy storage device comprising an electrodeaccording to claim
 32. 35-60. (canceled)
 61. A carbon material having asurface area of 100 to 2000 m²/g and a total pore volume, wherein lessthan 10% of the pore volume resides in micropores greater than 80% ofthe pore volume resides in mesopores volume and less than 5% of the porevolume resides in macropores. 62-66. (canceled)
 67. A method forproducing a composite a material comprising a porous scaffold materialand silicon comprising the following steps: a) providing a porousscaffold material, wherein the said porous scaffold material comprises10-50% of pores having a diameter from 50-200 A and greater than 90% ofpores having a diameter less than 200 A; and b) impregnating siliconwithin the porous scaffold material, thereby producing asilicon-impregnated scaffold material. 68-82. (canceled)